diff --git a/Marlin/Marlin_main.cpp b/Marlin/Marlin_main.cpp
index 35d739a5a2f62566c4135de84e7b691248192ceb..d244b198de57fb56158d536e46ea6a2cb36da91d 100644
--- a/Marlin/Marlin_main.cpp
+++ b/Marlin/Marlin_main.cpp
@@ -261,7 +261,7 @@
 #if HAS_ABL
   #include "vector_3.h"
   #if ENABLED(AUTO_BED_LEVELING_LINEAR)
-    #include "qr_solve.h"
+    #include "least_squares_fit.h"
   #endif
 #elif ENABLED(MESH_BED_LEVELING)
   #include "mesh_bed_leveling.h"
@@ -4336,8 +4336,8 @@ void home_all_axes() { gcode_G28(true); }
         ABL_VAR int indexIntoAB[GRID_MAX_POINTS_X][GRID_MAX_POINTS_Y];
 
         ABL_VAR float eqnAMatrix[GRID_MAX_POINTS * 3], // "A" matrix of the linear system of equations
-                     eqnBVector[GRID_MAX_POINTS],     // "B" vector of Z points
-                     mean;
+                      eqnBVector[GRID_MAX_POINTS],     // "B" vector of Z points
+                      mean;
       #endif
 
     #elif ENABLED(AUTO_BED_LEVELING_3POINT)
@@ -4353,6 +4353,11 @@ void home_all_axes() { gcode_G28(true); }
 
     #endif // AUTO_BED_LEVELING_3POINT
 
+    #if ENABLED(AUTO_BED_LEVELING_LINEAR)
+      struct linear_fit_data lsf_results;
+      incremental_LSF_reset(&lsf_results);
+    #endif
+
     /**
      * On the initial G29 fetch command parameters.
      */
@@ -4549,11 +4554,7 @@ void home_all_axes() { gcode_G28(true); }
           abl_should_enable = false;
         }
 
-      #elif ENABLED(AUTO_BED_LEVELING_LINEAR)
-
-        mean = 0.0;
-
-      #endif // AUTO_BED_LEVELING_LINEAR
+      #endif // AUTO_BED_LEVELING_BILINEAR
 
       #if ENABLED(AUTO_BED_LEVELING_3POINT)
 
@@ -4616,11 +4617,11 @@ void home_all_axes() { gcode_G28(true); }
 
         #if ENABLED(AUTO_BED_LEVELING_LINEAR)
 
-          mean += measured_z;
-          eqnBVector[abl_probe_index] = measured_z;
-          eqnAMatrix[abl_probe_index + 0 * abl2] = xProbe;
-          eqnAMatrix[abl_probe_index + 1 * abl2] = yProbe;
-          eqnAMatrix[abl_probe_index + 2 * abl2] = 1;
+//        mean += measured_z;                                  // I believe this is unused code?
+//        eqnBVector[abl_probe_index] = measured_z;            // I believe this is unused code?
+//        eqnAMatrix[abl_probe_index + 0 * abl2] = xProbe;     // I believe this is unused code?
+//        eqnAMatrix[abl_probe_index + 1 * abl2] = yProbe;     // I believe this is unused code?
+//        eqnAMatrix[abl_probe_index + 2 * abl2] = 1;          // I believe this is unused code?
 
         #elif ENABLED(AUTO_BED_LEVELING_BILINEAR)
 
@@ -4794,6 +4795,11 @@ void home_all_axes() { gcode_G28(true); }
               eqnAMatrix[abl_probe_index + 1 * abl2] = yProbe;
               eqnAMatrix[abl_probe_index + 2 * abl2] = 1;
 
+              incremental_LSF(&lsf_results, xProbe, yProbe, measured_z);
+
+          #if ENABLED(AUTO_BED_LEVELING_LINEAR)
+            indexIntoAB[xCount][yCount] = abl_probe_index;
+          #endif
             #elif ENABLED(AUTO_BED_LEVELING_BILINEAR)
 
               z_values[xCount][yCount] = measured_z + zoffset;
@@ -4894,7 +4900,11 @@ void home_all_axes() { gcode_G28(true); }
        * so Vx = -a Vy = -b Vz = 1 (we want the vector facing towards positive Z
        */
       float plane_equation_coefficients[3];
-      qr_solve(plane_equation_coefficients, abl2, 3, eqnAMatrix, eqnBVector);
+
+      finish_incremental_LSF(&lsf_results);
+      plane_equation_coefficients[0] = -lsf_results.A;  // We should be able to eliminate the '-' on these three lines and down below
+      plane_equation_coefficients[1] = -lsf_results.B;  // but that is not yet tested.
+      plane_equation_coefficients[2] = -lsf_results.D;
 
       mean /= abl2;
 
@@ -4916,7 +4926,7 @@ void home_all_axes() { gcode_G28(true); }
       // Create the matrix but don't correct the position yet
       if (!dryrun) {
         planner.bed_level_matrix = matrix_3x3::create_look_at(
-          vector_3(-plane_equation_coefficients[0], -plane_equation_coefficients[1], 1)
+          vector_3(-plane_equation_coefficients[0], -plane_equation_coefficients[1], 1)    // We can eleminate the '-' here and up above
         );
       }
 
diff --git a/Marlin/least_squares_fit.cpp b/Marlin/least_squares_fit.cpp
index 42adc8fe68d9ce2a6e0d4cf23c77e4f53423bd7d..f8c7a0b521fc7f7187dd7a8eaae066eaf6d7228b 100644
--- a/Marlin/least_squares_fit.cpp
+++ b/Marlin/least_squares_fit.cpp
@@ -34,7 +34,7 @@
 
 #include "MarlinConfig.h"
 
-#if ENABLED(AUTO_BED_LEVELING_UBL)  // Currently only used by UBL, but is applicable to Grid Based (Linear) Bed Leveling
+#if ENABLED(AUTO_BED_LEVELING_UBL) || ENABLED(AUTO_BED_LEVELING_LINEAR)
 
 #include "macros.h"
 #include <math.h>
@@ -68,4 +68,4 @@ int finish_incremental_LSF(struct linear_fit_data *lsf) {
   return 0;
 }
 
-#endif // AUTO_BED_LEVELING_UBL
+#endif // AUTO_BED_LEVELING_UBL || ENABLED(AUTO_BED_LEVELING_LINEAR)  
diff --git a/Marlin/least_squares_fit.h b/Marlin/least_squares_fit.h
index bdb42715978e693b7f4825d6406de2d6efd2cfea..00d7a241916eb4f42436958f5efb0ebc7ec92ea4 100644
--- a/Marlin/least_squares_fit.h
+++ b/Marlin/least_squares_fit.h
@@ -34,7 +34,7 @@
 
 #include "MarlinConfig.h"
 
-#if ENABLED(AUTO_BED_LEVELING_UBL)  // Currently only used by UBL, but is applicable to Grid Based (Linear) Bed Leveling
+#if ENABLED(AUTO_BED_LEVELING_UBL) || ENABLED(AUTO_BED_LEVELING_LINEAR)    
 
 #include "Marlin.h"
 #include "macros.h"
diff --git a/Marlin/qr_solve.cpp b/Marlin/qr_solve.cpp
deleted file mode 100644
index 7706c6f8cf50617b8a97cdd61a93a4fd0c3d677f..0000000000000000000000000000000000000000
--- a/Marlin/qr_solve.cpp
+++ /dev/null
@@ -1,1591 +0,0 @@
-/**
- * Marlin 3D Printer Firmware
- * Copyright (C) 2016 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
- *
- * Based on Sprinter and grbl.
- * Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- */
-
-#include "qr_solve.h"
-
-#if ENABLED(AUTO_BED_LEVELING_LINEAR)
-
-#include <stdlib.h>
-#include <math.h>
-
-//# include "r8lib.h"
-
-int i4_min(int i1, int i2)
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    I4_MIN returns the smaller of two I4's.
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    29 August 2006
-
-  Author:
-
-    John Burkardt
-
-  Parameters:
-
-    Input, int I1, I2, two integers to be compared.
-
-    Output, int I4_MIN, the smaller of I1 and I2.
-*/
-{
-  return (i1 < i2) ? i1 : i2;
-}
-
-float r8_epsilon(void)
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    R8_EPSILON returns the R8 round off unit.
-
-  Discussion:
-
-    R8_EPSILON is a number R which is a power of 2 with the property that,
-    to the precision of the computer's arithmetic,
-      1 < 1 + R
-    but
-      1 = ( 1 + R / 2 )
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    01 September 2012
-
-  Author:
-
-    John Burkardt
-
-  Parameters:
-
-    Output, float R8_EPSILON, the R8 round-off unit.
-*/
-{
-  const float value = 2.220446049250313E-016;
-  return value;
-}
-
-float r8_max(float x, float y)
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    R8_MAX returns the maximum of two R8's.
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    07 May 2006
-
-  Author:
-
-    John Burkardt
-
-  Parameters:
-
-    Input, float X, Y, the quantities to compare.
-
-    Output, float R8_MAX, the maximum of X and Y.
-*/
-{
-  return (y < x) ? x : y;
-}
-
-float r8_abs(float x)
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    R8_ABS returns the absolute value of an R8.
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    07 May 2006
-
-  Author:
-
-    John Burkardt
-
-  Parameters:
-
-    Input, float X, the quantity whose absolute value is desired.
-
-    Output, float R8_ABS, the absolute value of X.
-*/
-{
-  return (x < 0.0) ? -x : x;
-}
-
-float r8_sign(float x)
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    R8_SIGN returns the sign of an R8.
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    08 May 2006
-
-  Author:
-
-    John Burkardt
-
-  Parameters:
-
-    Input, float X, the number whose sign is desired.
-
-    Output, float R8_SIGN, the sign of X.
-*/
-{
-  return (x < 0.0) ? -1.0 : 1.0;
-}
-
-float r8mat_amax(int m, int n, float a[])
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    R8MAT_AMAX returns the maximum absolute value entry of an R8MAT.
-
-  Discussion:
-
-    An R8MAT is a doubly dimensioned array of R8 values, stored as a vector
-    in column-major order.
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    07 September 2012
-
-  Author:
-
-    John Burkardt
-
-  Parameters:
-
-    Input, int M, the number of rows in A.
-
-    Input, int N, the number of columns in A.
-
-    Input, float A[M*N], the M by N matrix.
-
-    Output, float R8MAT_AMAX, the maximum absolute value entry of A.
-*/
-{
-  float value = r8_abs(a[0 + 0 * m]);
-  for (int j = 0; j < n; j++) {
-    for (int i = 0; i < m; i++) {
-      NOLESS(value, r8_abs(a[i + j * m]));
-    }
-  }
-  return value;
-}
-
-void r8mat_copy(float a2[], int m, int n, float a1[])
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    R8MAT_COPY_NEW copies one R8MAT to a "new" R8MAT.
-
-  Discussion:
-
-    An R8MAT is a doubly dimensioned array of R8 values, stored as a vector
-    in column-major order.
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    26 July 2008
-
-  Author:
-
-    John Burkardt
-
-  Parameters:
-
-    Input, int M, N, the number of rows and columns.
-
-    Input, float A1[M*N], the matrix to be copied.
-
-    Output, float R8MAT_COPY_NEW[M*N], the copy of A1.
-*/
-{
-  for (int j = 0; j < n; j++) {
-    for (int i = 0; i < m; i++)
-      a2[i + j * m] = a1[i + j * m];
-  }
-}
-
-/******************************************************************************/
-
-void daxpy(int n, float da, float dx[], int incx, float dy[], int incy)
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    DAXPY computes constant times a vector plus a vector.
-
-  Discussion:
-
-    This routine uses unrolled loops for increments equal to one.
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    30 March 2007
-
-  Author:
-
-    C version by John Burkardt
-
-  Reference:
-
-    Jack Dongarra, Cleve Moler, Jim Bunch, Pete Stewart,
-    LINPACK User's Guide,
-    SIAM, 1979.
-
-    Charles Lawson, Richard Hanson, David Kincaid, Fred Krogh,
-    Basic Linear Algebra Subprograms for Fortran Usage,
-    Algorithm 539,
-    ACM Transactions on Mathematical Software,
-    Volume 5, Number 3, September 1979, pages 308-323.
-
-  Parameters:
-
-    Input, int N, the number of elements in DX and DY.
-
-    Input, float DA, the multiplier of DX.
-
-    Input, float DX[*], the first vector.
-
-    Input, int INCX, the increment between successive entries of DX.
-
-    Input/output, float DY[*], the second vector.
-    On output, DY[*] has been replaced by DY[*] + DA * DX[*].
-
-    Input, int INCY, the increment between successive entries of DY.
-*/
-{
-  if (n <= 0 || da == 0.0) return;
-
-  int i, ix, iy, m;
-  /**
-    Code for unequal increments or equal increments
-    not equal to 1.
-  */
-  if (incx != 1 || incy != 1) {
-    if (0 <= incx)
-      ix = 0;
-    else
-      ix = (- n + 1) * incx;
-    if (0 <= incy)
-      iy = 0;
-    else
-      iy = (- n + 1) * incy;
-    for (i = 0; i < n; i++) {
-      dy[iy] = dy[iy] + da * dx[ix];
-      ix = ix + incx;
-      iy = iy + incy;
-    }
-  }
-  /**
-    Code for both increments equal to 1.
-  */
-  else {
-    m = n % 4;
-    for (i = 0; i < m; i++)
-      dy[i] = dy[i] + da * dx[i];
-    for (i = m; i < n; i = i + 4) {
-      dy[i  ] = dy[i  ] + da * dx[i  ];
-      dy[i + 1] = dy[i + 1] + da * dx[i + 1];
-      dy[i + 2] = dy[i + 2] + da * dx[i + 2];
-      dy[i + 3] = dy[i + 3] + da * dx[i + 3];
-    }
-  }
-}
-/******************************************************************************/
-
-float ddot(int n, float dx[], int incx, float dy[], int incy)
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    DDOT forms the dot product of two vectors.
-
-  Discussion:
-
-    This routine uses unrolled loops for increments equal to one.
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    30 March 2007
-
-  Author:
-
-    C version by John Burkardt
-
-  Reference:
-
-    Jack Dongarra, Cleve Moler, Jim Bunch, Pete Stewart,
-    LINPACK User's Guide,
-    SIAM, 1979.
-
-    Charles Lawson, Richard Hanson, David Kincaid, Fred Krogh,
-    Basic Linear Algebra Subprograms for Fortran Usage,
-    Algorithm 539,
-    ACM Transactions on Mathematical Software,
-    Volume 5, Number 3, September 1979, pages 308-323.
-
-  Parameters:
-
-    Input, int N, the number of entries in the vectors.
-
-    Input, float DX[*], the first vector.
-
-    Input, int INCX, the increment between successive entries in DX.
-
-    Input, float DY[*], the second vector.
-
-    Input, int INCY, the increment between successive entries in DY.
-
-    Output, float DDOT, the sum of the product of the corresponding
-    entries of DX and DY.
-*/
-{
-
-  if (n <= 0) return 0.0;
-
-  int i, m;
-  float dtemp = 0.0;
-
-  /**
-    Code for unequal increments or equal increments
-    not equal to 1.
-  */
-  if (incx != 1 || incy != 1) {
-    int ix = (incx >= 0) ? 0 : (-n + 1) * incx,
-        iy = (incy >= 0) ? 0 : (-n + 1) * incy;
-    for (i = 0; i < n; i++) {
-      dtemp += dx[ix] * dy[iy];
-      ix = ix + incx;
-      iy = iy + incy;
-    }
-  }
-  /**
-    Code for both increments equal to 1.
-  */
-  else {
-    m = n % 5;
-    for (i = 0; i < m; i++)
-      dtemp += dx[i] * dy[i];
-    for (i = m; i < n; i = i + 5) {
-      dtemp += dx[i] * dy[i]
-              + dx[i + 1] * dy[i + 1]
-              + dx[i + 2] * dy[i + 2]
-              + dx[i + 3] * dy[i + 3]
-              + dx[i + 4] * dy[i + 4];
-    }
-  }
-  return dtemp;
-}
-/******************************************************************************/
-
-float dnrm2(int n, float x[], int incx)
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    DNRM2 returns the euclidean norm of a vector.
-
-  Discussion:
-
-     DNRM2 ( X ) = sqrt ( X' * X )
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    30 March 2007
-
-  Author:
-
-    C version by John Burkardt
-
-  Reference:
-
-    Jack Dongarra, Cleve Moler, Jim Bunch, Pete Stewart,
-    LINPACK User's Guide,
-    SIAM, 1979.
-
-    Charles Lawson, Richard Hanson, David Kincaid, Fred Krogh,
-    Basic Linear Algebra Subprograms for Fortran Usage,
-    Algorithm 539,
-    ACM Transactions on Mathematical Software,
-    Volume 5, Number 3, September 1979, pages 308-323.
-
-  Parameters:
-
-    Input, int N, the number of entries in the vector.
-
-    Input, float X[*], the vector whose norm is to be computed.
-
-    Input, int INCX, the increment between successive entries of X.
-
-    Output, float DNRM2, the Euclidean norm of X.
-*/
-{
-  float norm;
-  if (n < 1 || incx < 1)
-    norm = 0.0;
-  else if (n == 1)
-    norm = r8_abs(x[0]);
-  else {
-    float scale = 0.0, ssq = 1.0;
-    int ix = 0;
-    for (int i = 0; i < n; i++) {
-      if (x[ix] != 0.0) {
-        float absxi = r8_abs(x[ix]);
-        if (scale < absxi) {
-          ssq = 1.0 + ssq * (scale / absxi) * (scale / absxi);
-          scale = absxi;
-        }
-        else
-          ssq = ssq + (absxi / scale) * (absxi / scale);
-      }
-      ix += incx;
-    }
-    norm = scale * SQRT(ssq);
-  }
-  return norm;
-}
-/******************************************************************************/
-
-void dqrank(float a[], int lda, int m, int n, float tol, int* kr,
-            int jpvt[], float qraux[])
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    DQRANK computes the QR factorization of a rectangular matrix.
-
-  Discussion:
-
-    This routine is used in conjunction with DQRLSS to solve
-    overdetermined, underdetermined and singular linear systems
-    in a least squares sense.
-
-    DQRANK uses the LINPACK subroutine DQRDC to compute the QR
-    factorization, with column pivoting, of an M by N matrix A.
-    The numerical rank is determined using the tolerance TOL.
-
-    Note that on output, ABS ( A(1,1) ) / ABS ( A(KR,KR) ) is an estimate
-    of the condition number of the matrix of independent columns,
-    and of R.  This estimate will be <= 1/TOL.
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    21 April 2012
-
-  Author:
-
-    C version by John Burkardt.
-
-  Reference:
-
-    Jack Dongarra, Cleve Moler, Jim Bunch, Pete Stewart,
-    LINPACK User's Guide,
-    SIAM, 1979,
-    ISBN13: 978-0-898711-72-1,
-    LC: QA214.L56.
-
-  Parameters:
-
-    Input/output, float A[LDA*N].  On input, the matrix whose
-    decomposition is to be computed.  On output, the information from DQRDC.
-    The triangular matrix R of the QR factorization is contained in the
-    upper triangle and information needed to recover the orthogonal
-    matrix Q is stored below the diagonal in A and in the vector QRAUX.
-
-    Input, int LDA, the leading dimension of A, which must
-    be at least M.
-
-    Input, int M, the number of rows of A.
-
-    Input, int N, the number of columns of A.
-
-    Input, float TOL, a relative tolerance used to determine the
-    numerical rank.  The problem should be scaled so that all the elements
-    of A have roughly the same absolute accuracy, EPS.  Then a reasonable
-    value for TOL is roughly EPS divided by the magnitude of the largest
-    element.
-
-    Output, int *KR, the numerical rank.
-
-    Output, int JPVT[N], the pivot information from DQRDC.
-    Columns JPVT(1), ..., JPVT(KR) of the original matrix are linearly
-    independent to within the tolerance TOL and the remaining columns
-    are linearly dependent.
-
-    Output, float QRAUX[N], will contain extra information defining
-    the QR factorization.
-*/
-{
-  float work[n];
-
-  for (int i = 0; i < n; i++)
-    jpvt[i] = 0;
-
-  int job = 1;
-
-  dqrdc(a, lda, m, n, qraux, jpvt, work, job);
-
-  *kr = 0;
-  int k = i4_min(m, n);
-  for (int j = 0; j < k; j++) {
-    if (r8_abs(a[j + j * lda]) <= tol * r8_abs(a[0 + 0 * lda]))
-      return;
-    *kr = j + 1;
-  }
-}
-/******************************************************************************/
-
-void dqrdc(float a[], int lda, int n, int p, float qraux[], int jpvt[],
-           float work[], int job)
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    DQRDC computes the QR factorization of a real rectangular matrix.
-
-  Discussion:
-
-    DQRDC uses Householder transformations.
-
-    Column pivoting based on the 2-norms of the reduced columns may be
-    performed at the user's option.
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    07 June 2005
-
-  Author:
-
-    C version by John Burkardt.
-
-  Reference:
-
-    Jack Dongarra, Cleve Moler, Jim Bunch and Pete Stewart,
-    LINPACK User's Guide,
-    SIAM, (Society for Industrial and Applied Mathematics),
-    3600 University City Science Center,
-    Philadelphia, PA, 19104-2688.
-    ISBN 0-89871-172-X
-
-  Parameters:
-
-    Input/output, float A(LDA,P).  On input, the N by P matrix
-    whose decomposition is to be computed.  On output, A contains in
-    its upper triangle the upper triangular matrix R of the QR
-    factorization.  Below its diagonal A contains information from
-    which the orthogonal part of the decomposition can be recovered.
-    Note that if pivoting has been requested, the decomposition is not that
-    of the original matrix A but that of A with its columns permuted
-    as described by JPVT.
-
-    Input, int LDA, the leading dimension of the array A.  LDA must
-    be at least N.
-
-    Input, int N, the number of rows of the matrix A.
-
-    Input, int P, the number of columns of the matrix A.
-
-    Output, float QRAUX[P], contains further information required
-    to recover the orthogonal part of the decomposition.
-
-    Input/output, integer JPVT[P].  On input, JPVT contains integers that
-    control the selection of the pivot columns.  The K-th column A(*,K) of A
-    is placed in one of three classes according to the value of JPVT(K).
-      > 0, then A(K) is an initial column.
-      = 0, then A(K) is a free column.
-      < 0, then A(K) is a final column.
-    Before the decomposition is computed, initial columns are moved to
-    the beginning of the array A and final columns to the end.  Both
-    initial and final columns are frozen in place during the computation
-    and only free columns are moved.  At the K-th stage of the
-    reduction, if A(*,K) is occupied by a free column it is interchanged
-    with the free column of largest reduced norm.  JPVT is not referenced
-    if JOB == 0.  On output, JPVT(K) contains the index of the column of the
-    original matrix that has been interchanged into the K-th column, if
-    pivoting was requested.
-
-    Workspace, float WORK[P].  WORK is not referenced if JOB == 0.
-
-    Input, int JOB, initiates column pivoting.
-    0, no pivoting is done.
-    nonzero, pivoting is done.
-*/
-{
-  int jp;
-  int j;
-  int lup;
-  int maxj;
-  float maxnrm, nrmxl, t, tt;
-
-  int pl = 1, pu = 0;
-  /**
-    If pivoting is requested, rearrange the columns.
-  */
-  if (job != 0) {
-    for (j = 1; j <= p; j++) {
-      int swapj = (0 < jpvt[j - 1]);
-      jpvt[j - 1] = (jpvt[j - 1] < 0) ? -j : j;
-      if (swapj) {
-        if (j != pl)
-          dswap(n, a + 0 + (pl - 1)*lda, 1, a + 0 + (j - 1), 1);
-        jpvt[j - 1] = jpvt[pl - 1];
-        jpvt[pl - 1] = j;
-        pl++;
-      }
-    }
-    pu = p;
-    for (j = p; 1 <= j; j--) {
-      if (jpvt[j - 1] < 0) {
-        jpvt[j - 1] = -jpvt[j - 1];
-        if (j != pu) {
-          dswap(n, a + 0 + (pu - 1)*lda, 1, a + 0 + (j - 1)*lda, 1);
-          jp = jpvt[pu - 1];
-          jpvt[pu - 1] = jpvt[j - 1];
-          jpvt[j - 1] = jp;
-        }
-        pu = pu - 1;
-      }
-    }
-  }
-  /**
-    Compute the norms of the free columns.
-  */
-  for (j = pl; j <= pu; j++)
-    qraux[j - 1] = dnrm2(n, a + 0 + (j - 1) * lda, 1);
-  for (j = pl; j <= pu; j++)
-    work[j - 1] = qraux[j - 1];
-  /**
-    Perform the Householder reduction of A.
-  */
-  lup = i4_min(n, p);
-  for (int l = 1; l <= lup; l++) {
-    /**
-      Bring the column of largest norm into the pivot position.
-    */
-    if (pl <= l && l < pu) {
-      maxnrm = 0.0;
-      maxj = l;
-      for (j = l; j <= pu; j++) {
-        if (maxnrm < qraux[j - 1]) {
-          maxnrm = qraux[j - 1];
-          maxj = j;
-        }
-      }
-      if (maxj != l) {
-        dswap(n, a + 0 + (l - 1)*lda, 1, a + 0 + (maxj - 1)*lda, 1);
-        qraux[maxj - 1] = qraux[l - 1];
-        work[maxj - 1] = work[l - 1];
-        jp = jpvt[maxj - 1];
-        jpvt[maxj - 1] = jpvt[l - 1];
-        jpvt[l - 1] = jp;
-      }
-    }
-    /**
-      Compute the Householder transformation for column L.
-    */
-    qraux[l - 1] = 0.0;
-    if (l != n) {
-      nrmxl = dnrm2(n - l + 1, a + l - 1 + (l - 1) * lda, 1);
-      if (nrmxl != 0.0) {
-        if (a[l - 1 + (l - 1)*lda] != 0.0)
-          nrmxl = nrmxl * r8_sign(a[l - 1 + (l - 1) * lda]);
-        dscal(n - l + 1, 1.0 / nrmxl, a + l - 1 + (l - 1)*lda, 1);
-        a[l - 1 + (l - 1)*lda] = 1.0 + a[l - 1 + (l - 1) * lda];
-        /**
-          Apply the transformation to the remaining columns, updating the norms.
-        */
-        for (j = l + 1; j <= p; j++) {
-          t = -ddot(n - l + 1, a + l - 1 + (l - 1) * lda, 1, a + l - 1 + (j - 1) * lda, 1)
-              / a[l - 1 + (l - 1) * lda];
-          daxpy(n - l + 1, t, a + l - 1 + (l - 1)*lda, 1, a + l - 1 + (j - 1)*lda, 1);
-          if (pl <= j && j <= pu) {
-            if (qraux[j - 1] != 0.0) {
-              tt = 1.0 - POW(r8_abs(a[l - 1 + (j - 1) * lda]) / qraux[j - 1], 2);
-              tt = r8_max(tt, 0.0);
-              t = tt;
-              tt = 1.0 + 0.05 * tt * POW(qraux[j - 1] / work[j - 1], 2);
-              if (tt != 1.0)
-                qraux[j - 1] = qraux[j - 1] * SQRT(t);
-              else {
-                qraux[j - 1] = dnrm2(n - l, a + l + (j - 1) * lda, 1);
-                work[j - 1] = qraux[j - 1];
-              }
-            }
-          }
-        }
-        /**
-          Save the transformation.
-        */
-        qraux[l - 1] = a[l - 1 + (l - 1) * lda];
-        a[l - 1 + (l - 1)*lda] = -nrmxl;
-      }
-    }
-  }
-}
-/******************************************************************************/
-
-int dqrls(float a[], int lda, int m, int n, float tol, int* kr, float b[],
-          float x[], float rsd[], int jpvt[], float qraux[], int itask)
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    DQRLS factors and solves a linear system in the least squares sense.
-
-  Discussion:
-
-    The linear system may be overdetermined, underdetermined or singular.
-    The solution is obtained using a QR factorization of the
-    coefficient matrix.
-
-    DQRLS can be efficiently used to solve several least squares
-    problems with the same matrix A.  The first system is solved
-    with ITASK = 1.  The subsequent systems are solved with
-    ITASK = 2, to avoid the recomputation of the matrix factors.
-    The parameters KR, JPVT, and QRAUX must not be modified
-    between calls to DQRLS.
-
-    DQRLS is used to solve in a least squares sense
-    overdetermined, underdetermined and singular linear systems.
-    The system is A*X approximates B where A is M by N.
-    B is a given M-vector, and X is the N-vector to be computed.
-    A solution X is found which minimimzes the sum of squares (2-norm)
-    of the residual,  A*X - B.
-
-    The numerical rank of A is determined using the tolerance TOL.
-
-    DQRLS uses the LINPACK subroutine DQRDC to compute the QR
-    factorization, with column pivoting, of an M by N matrix A.
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    10 September 2012
-
-  Author:
-
-    C version by John Burkardt.
-
-  Reference:
-
-    David Kahaner, Cleve Moler, Steven Nash,
-    Numerical Methods and Software,
-    Prentice Hall, 1989,
-    ISBN: 0-13-627258-4,
-    LC: TA345.K34.
-
-  Parameters:
-
-    Input/output, float A[LDA*N], an M by N matrix.
-    On input, the matrix whose decomposition is to be computed.
-    In a least squares data fitting problem, A(I,J) is the
-    value of the J-th basis (model) function at the I-th data point.
-    On output, A contains the output from DQRDC.  The triangular matrix R
-    of the QR factorization is contained in the upper triangle and
-    information needed to recover the orthogonal matrix Q is stored
-    below the diagonal in A and in the vector QRAUX.
-
-    Input, int LDA, the leading dimension of A.
-
-    Input, int M, the number of rows of A.
-
-    Input, int N, the number of columns of A.
-
-    Input, float TOL, a relative tolerance used to determine the
-    numerical rank.  The problem should be scaled so that all the elements
-    of A have roughly the same absolute accuracy EPS.  Then a reasonable
-    value for TOL is roughly EPS divided by the magnitude of the largest
-    element.
-
-    Output, int *KR, the numerical rank.
-
-    Input, float B[M], the right hand side of the linear system.
-
-    Output, float X[N], a least squares solution to the linear
-    system.
-
-    Output, float RSD[M], the residual, B - A*X.  RSD may
-    overwrite B.
-
-    Workspace, int JPVT[N], required if ITASK = 1.
-    Columns JPVT(1), ..., JPVT(KR) of the original matrix are linearly
-    independent to within the tolerance TOL and the remaining columns
-    are linearly dependent.  ABS ( A(1,1) ) / ABS ( A(KR,KR) ) is an estimate
-    of the condition number of the matrix of independent columns,
-    and of R.  This estimate will be <= 1/TOL.
-
-    Workspace, float QRAUX[N], required if ITASK = 1.
-
-    Input, int ITASK.
-    1, DQRLS factors the matrix A and solves the least squares problem.
-    2, DQRLS assumes that the matrix A was factored with an earlier
-       call to DQRLS, and only solves the least squares problem.
-
-    Output, int DQRLS, error code.
-    0:  no error
-    -1: LDA < M   (fatal error)
-    -2: N < 1     (fatal error)
-    -3: ITASK < 1 (fatal error)
-*/
-{
-  int ind;
-  if (lda < m) {
-    /*fprintf ( stderr, "\n" );
-    fprintf ( stderr, "DQRLS - Fatal error!\n" );
-    fprintf ( stderr, "  LDA < M.\n" );*/
-    ind = -1;
-    return ind;
-  }
-
-  if (n <= 0) {
-    /*fprintf ( stderr, "\n" );
-    fprintf ( stderr, "DQRLS - Fatal error!\n" );
-    fprintf ( stderr, "  N <= 0.\n" );*/
-    ind = -2;
-    return ind;
-  }
-
-  if (itask < 1) {
-    /*fprintf ( stderr, "\n" );
-    fprintf ( stderr, "DQRLS - Fatal error!\n" );
-    fprintf ( stderr, "  ITASK < 1.\n" );*/
-    ind = -3;
-    return ind;
-  }
-
-  ind = 0;
-  /**
-    Factor the matrix.
-  */
-  if (itask == 1)
-    dqrank(a, lda, m, n, tol, kr, jpvt, qraux);
-  /**
-    Solve the least-squares problem.
-  */
-  dqrlss(a, lda, m, n, *kr, b, x, rsd, jpvt, qraux);
-  return ind;
-}
-/******************************************************************************/
-
-void dqrlss(float a[], int lda, int m, int n, int kr, float b[], float x[],
-            float rsd[], int jpvt[], float qraux[])
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    DQRLSS solves a linear system in a least squares sense.
-
-  Discussion:
-
-    DQRLSS must be preceded by a call to DQRANK.
-
-    The system is to be solved is
-      A * X = B
-    where
-      A is an M by N matrix with rank KR, as determined by DQRANK,
-      B is a given M-vector,
-      X is the N-vector to be computed.
-
-    A solution X, with at most KR nonzero components, is found which
-    minimizes the 2-norm of the residual (A*X-B).
-
-    Once the matrix A has been formed, DQRANK should be
-    called once to decompose it.  Then, for each right hand
-    side B, DQRLSS should be called once to obtain the
-    solution and residual.
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    10 September 2012
-
-  Author:
-
-    C version by John Burkardt
-
-  Parameters:
-
-    Input, float A[LDA*N], the QR factorization information
-    from DQRANK.  The triangular matrix R of the QR factorization is
-    contained in the upper triangle and information needed to recover
-    the orthogonal matrix Q is stored below the diagonal in A and in
-    the vector QRAUX.
-
-    Input, int LDA, the leading dimension of A, which must
-    be at least M.
-
-    Input, int M, the number of rows of A.
-
-    Input, int N, the number of columns of A.
-
-    Input, int KR, the rank of the matrix, as estimated by DQRANK.
-
-    Input, float B[M], the right hand side of the linear system.
-
-    Output, float X[N], a least squares solution to the
-    linear system.
-
-    Output, float RSD[M], the residual, B - A*X.  RSD may
-    overwrite B.
-
-    Input, int JPVT[N], the pivot information from DQRANK.
-    Columns JPVT[0], ..., JPVT[KR-1] of the original matrix are linearly
-    independent to within the tolerance TOL and the remaining columns
-    are linearly dependent.
-
-    Input, float QRAUX[N], auxiliary information from DQRANK
-    defining the QR factorization.
-*/
-{
-  int i;
-  int info;
-  int j;
-  int job;
-  int k;
-  float t;
-
-  if (kr != 0) {
-    job = 110;
-    info = dqrsl(a, lda, m, kr, qraux, b, rsd, rsd, x, rsd, rsd, job); UNUSED(info);
-  }
-
-  for (i = 0; i < n; i++)
-    jpvt[i] = - jpvt[i];
-
-  for (i = kr; i < n; i++)
-    x[i] = 0.0;
-
-  for (j = 1; j <= n; j++) {
-    if (jpvt[j - 1] <= 0) {
-      k = - jpvt[j - 1];
-      jpvt[j - 1] = k;
-
-      while (k != j) {
-        t = x[j - 1];
-        x[j - 1] = x[k - 1];
-        x[k - 1] = t;
-        jpvt[k - 1] = -jpvt[k - 1];
-        k = jpvt[k - 1];
-      }
-    }
-  }
-}
-/******************************************************************************/
-
-int dqrsl(float a[], int lda, int n, int k, float qraux[], float y[],
-          float qy[], float qty[], float b[], float rsd[], float ab[], int job)
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    DQRSL computes transformations, projections, and least squares solutions.
-
-  Discussion:
-
-    DQRSL requires the output of DQRDC.
-
-    For K <= min(N,P), let AK be the matrix
-
-      AK = ( A(JPVT[0]), A(JPVT(2)), ..., A(JPVT(K)) )
-
-    formed from columns JPVT[0], ..., JPVT(K) of the original
-    N by P matrix A that was input to DQRDC.  If no pivoting was
-    done, AK consists of the first K columns of A in their
-    original order.  DQRDC produces a factored orthogonal matrix Q
-    and an upper triangular matrix R such that
-
-      AK = Q * (R)
-               (0)
-
-    This information is contained in coded form in the arrays
-    A and QRAUX.
-
-    The parameters QY, QTY, B, RSD, and AB are not referenced
-    if their computation is not requested and in this case
-    can be replaced by dummy variables in the calling program.
-    To save storage, the user may in some cases use the same
-    array for different parameters in the calling sequence.  A
-    frequently occurring example is when one wishes to compute
-    any of B, RSD, or AB and does not need Y or QTY.  In this
-    case one may identify Y, QTY, and one of B, RSD, or AB, while
-    providing separate arrays for anything else that is to be
-    computed.
-
-    Thus the calling sequence
-
-      dqrsl ( a, lda, n, k, qraux, y, dum, y, b, y, dum, 110, info )
-
-    will result in the computation of B and RSD, with RSD
-    overwriting Y.  More generally, each item in the following
-    list contains groups of permissible identifications for
-    a single calling sequence.
-
-      1. (Y,QTY,B) (RSD) (AB) (QY)
-
-      2. (Y,QTY,RSD) (B) (AB) (QY)
-
-      3. (Y,QTY,AB) (B) (RSD) (QY)
-
-      4. (Y,QY) (QTY,B) (RSD) (AB)
-
-      5. (Y,QY) (QTY,RSD) (B) (AB)
-
-      6. (Y,QY) (QTY,AB) (B) (RSD)
-
-    In any group the value returned in the array allocated to
-    the group corresponds to the last member of the group.
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    07 June 2005
-
-  Author:
-
-    C version by John Burkardt.
-
-  Reference:
-
-    Jack Dongarra, Cleve Moler, Jim Bunch and Pete Stewart,
-    LINPACK User's Guide,
-    SIAM, (Society for Industrial and Applied Mathematics),
-    3600 University City Science Center,
-    Philadelphia, PA, 19104-2688.
-    ISBN 0-89871-172-X
-
-  Parameters:
-
-    Input, float A[LDA*P], contains the output of DQRDC.
-
-    Input, int LDA, the leading dimension of the array A.
-
-    Input, int N, the number of rows of the matrix AK.  It must
-    have the same value as N in DQRDC.
-
-    Input, int K, the number of columns of the matrix AK.  K
-    must not be greater than min(N,P), where P is the same as in the
-    calling sequence to DQRDC.
-
-    Input, float QRAUX[P], the auxiliary output from DQRDC.
-
-    Input, float Y[N], a vector to be manipulated by DQRSL.
-
-    Output, float QY[N], contains Q * Y, if requested.
-
-    Output, float QTY[N], contains Q' * Y, if requested.
-
-    Output, float B[K], the solution of the least squares problem
-      minimize norm2 ( Y - AK * B),
-    if its computation has been requested.  Note that if pivoting was
-    requested in DQRDC, the J-th component of B will be associated with
-    column JPVT(J) of the original matrix A that was input into DQRDC.
-
-    Output, float RSD[N], the least squares residual Y - AK * B,
-    if its computation has been requested.  RSD is also the orthogonal
-    projection of Y onto the orthogonal complement of the column space
-    of AK.
-
-    Output, float AB[N], the least squares approximation Ak * B,
-    if its computation has been requested.  AB is also the orthogonal
-    projection of Y onto the column space of A.
-
-    Input, integer JOB, specifies what is to be computed.  JOB has
-    the decimal expansion ABCDE, with the following meaning:
-
-      if A != 0, compute QY.
-      if B != 0, compute QTY.
-      if C != 0, compute QTY and B.
-      if D != 0, compute QTY and RSD.
-      if E != 0, compute QTY and AB.
-
-    Note that a request to compute B, RSD, or AB automatically triggers
-    the computation of QTY, for which an array must be provided in the
-    calling sequence.
-
-    Output, int DQRSL, is zero unless the computation of B has
-    been requested and R is exactly singular.  In this case, INFO is the
-    index of the first zero diagonal element of R, and B is left unaltered.
-*/
-{
-  int cab;
-  int cb;
-  int cqty;
-  int cqy;
-  int cr;
-  int i;
-  int info;
-  int j;
-  int jj;
-  int ju;
-  float t;
-  float temp;
-  /**
-    Set INFO flag.
-  */
-  info = 0;
-
-  /**
-    Determine what is to be computed.
-  */
-  cqy  = ( job / 10000        != 0);
-  cqty = ((job % 10000)       != 0);
-  cb   = ((job %  1000) / 100 != 0);
-  cr   = ((job %   100) /  10 != 0);
-  cab  = ((job %    10)       != 0);
-  ju = i4_min(k, n - 1);
-
-  /**
-    Special action when N = 1.
-  */
-  if (ju == 0) {
-    if (cqy)
-      qy[0] = y[0];
-    if (cqty)
-      qty[0] = y[0];
-    if (cab)
-      ab[0] = y[0];
-    if (cb) {
-      if (a[0 + 0 * lda] == 0.0)
-        info = 1;
-      else
-        b[0] = y[0] / a[0 + 0 * lda];
-    }
-    if (cr)
-      rsd[0] = 0.0;
-    return info;
-  }
-  /**
-    Set up to compute QY or QTY.
-  */
-  if (cqy) {
-    for (i = 1; i <= n; i++)
-      qy[i - 1] = y[i - 1];
-  }
-  if (cqty) {
-    for (i = 1; i <= n; i++)
-      qty[i - 1] = y[i - 1];
-  }
-  /**
-    Compute QY.
-  */
-  if (cqy) {
-    for (jj = 1; jj <= ju; jj++) {
-      j = ju - jj + 1;
-      if (qraux[j - 1] != 0.0) {
-        temp = a[j - 1 + (j - 1) * lda];
-        a[j - 1 + (j - 1)*lda] = qraux[j - 1];
-        t = -ddot(n - j + 1, a + j - 1 + (j - 1) * lda, 1, qy + j - 1, 1) / a[j - 1 + (j - 1) * lda];
-        daxpy(n - j + 1, t, a + j - 1 + (j - 1)*lda, 1, qy + j - 1, 1);
-        a[j - 1 + (j - 1)*lda] = temp;
-      }
-    }
-  }
-  /**
-    Compute Q'*Y.
-  */
-  if (cqty) {
-    for (j = 1; j <= ju; j++) {
-      if (qraux[j - 1] != 0.0) {
-        temp = a[j - 1 + (j - 1) * lda];
-        a[j - 1 + (j - 1)*lda] = qraux[j - 1];
-        t = -ddot(n - j + 1, a + j - 1 + (j - 1) * lda, 1, qty + j - 1, 1) / a[j - 1 + (j - 1) * lda];
-        daxpy(n - j + 1, t, a + j - 1 + (j - 1)*lda, 1, qty + j - 1, 1);
-        a[j - 1 + (j - 1)*lda] = temp;
-      }
-    }
-  }
-  /**
-    Set up to compute B, RSD, or AB.
-  */
-  if (cb) {
-    for (i = 1; i <= k; i++)
-      b[i - 1] = qty[i - 1];
-  }
-  if (cab) {
-    for (i = 1; i <= k; i++)
-      ab[i - 1] = qty[i - 1];
-  }
-  if (cr && k < n) {
-    for (i = k + 1; i <= n; i++)
-      rsd[i - 1] = qty[i - 1];
-  }
-  if (cab && k + 1 <= n) {
-    for (i = k + 1; i <= n; i++)
-      ab[i - 1] = 0.0;
-  }
-  if (cr) {
-    for (i = 1; i <= k; i++)
-      rsd[i - 1] = 0.0;
-  }
-  /**
-    Compute B.
-  */
-  if (cb) {
-    for (jj = 1; jj <= k; jj++) {
-      j = k - jj + 1;
-      if (a[j - 1 + (j - 1)*lda] == 0.0) {
-        info = j;
-        break;
-      }
-      b[j - 1] = b[j - 1] / a[j - 1 + (j - 1) * lda];
-      if (j != 1) {
-        t = -b[j - 1];
-        daxpy(j - 1, t, a + 0 + (j - 1)*lda, 1, b, 1);
-      }
-    }
-  }
-  /**
-    Compute RSD or AB as required.
-  */
-  if (cr || cab) {
-    for (jj = 1; jj <= ju; jj++) {
-      j = ju - jj + 1;
-      if (qraux[j - 1] != 0.0) {
-        temp = a[j - 1 + (j - 1) * lda];
-        a[j - 1 + (j - 1)*lda] = qraux[j - 1];
-        if (cr) {
-          t = -ddot(n - j + 1, a + j - 1 + (j - 1) * lda, 1, rsd + j - 1, 1)
-              / a[j - 1 + (j - 1) * lda];
-          daxpy(n - j + 1, t, a + j - 1 + (j - 1)*lda, 1, rsd + j - 1, 1);
-        }
-        if (cab) {
-          t = -ddot(n - j + 1, a + j - 1 + (j - 1) * lda, 1, ab + j - 1, 1)
-              / a[j - 1 + (j - 1) * lda];
-          daxpy(n - j + 1, t, a + j - 1 + (j - 1)*lda, 1, ab + j - 1, 1);
-        }
-        a[j - 1 + (j - 1)*lda] = temp;
-      }
-    }
-  }
-  return info;
-}
-/******************************************************************************/
-
-/******************************************************************************/
-
-void dscal(int n, float sa, float x[], int incx)
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    DSCAL scales a vector by a constant.
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    30 March 2007
-
-  Author:
-
-    C version by John Burkardt
-
-  Reference:
-
-    Jack Dongarra, Cleve Moler, Jim Bunch, Pete Stewart,
-    LINPACK User's Guide,
-    SIAM, 1979.
-
-    Charles Lawson, Richard Hanson, David Kincaid, Fred Krogh,
-    Basic Linear Algebra Subprograms for Fortran Usage,
-    Algorithm 539,
-    ACM Transactions on Mathematical Software,
-    Volume 5, Number 3, September 1979, pages 308-323.
-
-  Parameters:
-
-    Input, int N, the number of entries in the vector.
-
-    Input, float SA, the multiplier.
-
-    Input/output, float X[*], the vector to be scaled.
-
-    Input, int INCX, the increment between successive entries of X.
-*/
-{
-  int i;
-  int ix;
-  int m;
-
-  if (n <= 0) return;
-
-  if (incx == 1) {
-    m = n % 5;
-    for (i = 0; i < m; i++)
-      x[i] = sa * x[i];
-    for (i = m; i < n; i = i + 5) {
-      x[i]   = sa * x[i];
-      x[i + 1] = sa * x[i + 1];
-      x[i + 2] = sa * x[i + 2];
-      x[i + 3] = sa * x[i + 3];
-      x[i + 4] = sa * x[i + 4];
-    }
-  }
-  else {
-    if (0 <= incx)
-      ix = 0;
-    else
-      ix = (- n + 1) * incx;
-    for (i = 0; i < n; i++) {
-      x[ix] = sa * x[ix];
-      ix = ix + incx;
-    }
-  }
-}
-/******************************************************************************/
-
-
-void dswap(int n, float x[], int incx, float y[], int incy)
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    DSWAP interchanges two vectors.
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    30 March 2007
-
-  Author:
-
-    C version by John Burkardt
-
-  Reference:
-
-    Jack Dongarra, Cleve Moler, Jim Bunch, Pete Stewart,
-    LINPACK User's Guide,
-    SIAM, 1979.
-
-    Charles Lawson, Richard Hanson, David Kincaid, Fred Krogh,
-    Basic Linear Algebra Subprograms for Fortran Usage,
-    Algorithm 539,
-    ACM Transactions on Mathematical Software,
-    Volume 5, Number 3, September 1979, pages 308-323.
-
-  Parameters:
-
-    Input, int N, the number of entries in the vectors.
-
-    Input/output, float X[*], one of the vectors to swap.
-
-    Input, int INCX, the increment between successive entries of X.
-
-    Input/output, float Y[*], one of the vectors to swap.
-
-    Input, int INCY, the increment between successive elements of Y.
-*/
-{
-  if (n <= 0) return;
-
-  int i, ix, iy, m;
-  float temp;
-
-  if (incx == 1 && incy == 1) {
-    m = n % 3;
-    for (i = 0; i < m; i++) {
-      temp = x[i];
-      x[i] = y[i];
-      y[i] = temp;
-    }
-    for (i = m; i < n; i = i + 3) {
-      temp = x[i];
-      x[i] = y[i];
-      y[i] = temp;
-      temp = x[i + 1];
-      x[i + 1] = y[i + 1];
-      y[i + 1] = temp;
-      temp = x[i + 2];
-      x[i + 2] = y[i + 2];
-      y[i + 2] = temp;
-    }
-  }
-  else {
-    ix = (incx >= 0) ? 0 : (-n + 1) * incx;
-    iy = (incy >= 0) ? 0 : (-n + 1) * incy;
-    for (i = 0; i < n; i++) {
-      temp = x[ix];
-      x[ix] = y[iy];
-      y[iy] = temp;
-      ix = ix + incx;
-      iy = iy + incy;
-    }
-  }
-}
-/******************************************************************************/
-
-/******************************************************************************/
-
-void qr_solve(float x[], int m, int n, float a[], float b[])
-
-/******************************************************************************/
-/**
-  Purpose:
-
-    QR_SOLVE solves a linear system in the least squares sense.
-
-  Discussion:
-
-    If the matrix A has full column rank, then the solution X should be the
-    unique vector that minimizes the Euclidean norm of the residual.
-
-    If the matrix A does not have full column rank, then the solution is
-    not unique; the vector X will minimize the residual norm, but so will
-    various other vectors.
-
-  Licensing:
-
-    This code is distributed under the GNU LGPL license.
-
-  Modified:
-
-    11 September 2012
-
-  Author:
-
-    John Burkardt
-
-  Reference:
-
-    David Kahaner, Cleve Moler, Steven Nash,
-    Numerical Methods and Software,
-    Prentice Hall, 1989,
-    ISBN: 0-13-627258-4,
-    LC: TA345.K34.
-
-  Parameters:
-
-    Input, int M, the number of rows of A.
-
-    Input, int N, the number of columns of A.
-
-    Input, float A[M*N], the matrix.
-
-    Input, float B[M], the right hand side.
-
-    Output, float QR_SOLVE[N], the least squares solution.
-*/
-{
-  float a_qr[n * m], qraux[n], r[m], tol;
-  int ind, itask, jpvt[n], kr, lda;
-
-  r8mat_copy(a_qr, m, n, a);
-  lda = m;
-  tol = r8_epsilon() / r8mat_amax(m, n, a_qr);
-  itask = 1;
-
-  ind = dqrls(a_qr, lda, m, n, tol, &kr, b, x, r, jpvt, qraux, itask); UNUSED(ind);
-}
-/******************************************************************************/
-
-#endif
diff --git a/Marlin/qr_solve.h b/Marlin/qr_solve.h
deleted file mode 100644
index c409220d314b90c346c5d2efcff435744a22ffe3..0000000000000000000000000000000000000000
--- a/Marlin/qr_solve.h
+++ /dev/null
@@ -1,44 +0,0 @@
-/**
- * Marlin 3D Printer Firmware
- * Copyright (C) 2016 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
- *
- * Based on Sprinter and grbl.
- * Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- */
-
-#include "MarlinConfig.h"
-
-#if ENABLED(AUTO_BED_LEVELING_LINEAR)
-
-void daxpy(int n, float da, float dx[], int incx, float dy[], int incy);
-float ddot(int n, float dx[], int incx, float dy[], int incy);
-float dnrm2(int n, float x[], int incx);
-void dqrank(float a[], int lda, int m, int n, float tol, int* kr,
-            int jpvt[], float qraux[]);
-void dqrdc(float a[], int lda, int n, int p, float qraux[], int jpvt[],
-           float work[], int job);
-int dqrls(float a[], int lda, int m, int n, float tol, int* kr, float b[],
-          float x[], float rsd[], int jpvt[], float qraux[], int itask);
-void dqrlss(float a[], int lda, int m, int n, int kr, float b[], float x[],
-            float rsd[], int jpvt[], float qraux[]);
-int dqrsl(float a[], int lda, int n, int k, float qraux[], float y[],
-          float qy[], float qty[], float b[], float rsd[], float ab[], int job);
-void dscal(int n, float sa, float x[], int incx);
-void dswap(int n, float x[], int incx, float y[], int incy);
-void qr_solve(float x[], int m, int n, float a[], float b[]);
-
-#endif