# HG changeset patch
# User Michiel Broek <mbroek@mbse.eu>
# Date 1697302247 -7200
# Node ID 7f2ec2bc9d2e1de4c53713c94129555bfda7d4b3
# Parent  fa07b6c6238a47f0eba877a525544eb99fb9134d
Added polyfit files.

diff -r fa07b6c6238a -r 7f2ec2bc9d2e src/polyfit.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/polyfit.cpp	Sat Oct 14 18:50:47 2023 +0200
@@ -0,0 +1,318 @@
+/**
+ * @brief Simple polynomial fitting functions.
+ * @file polyfit.cpp
+ * @autor Henry M. Forson, Melbourne, Florida USA
+ *
+ *------------------------------------------------------------------------------------
+ * MIT License
+ *
+ * Copyright (c) 2020 Henry M. Forson
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *------------------------------------------------------------------------------------
+ */
+
+#include "polyfit.h"
+
+#include <QDebug>
+#include <math.h>
+
+
+
+// Structure of a matrix.
+typedef struct matrix_s
+{
+	int	rows;
+	int	cols;
+	double *pContents;
+} matrix_t;
+
+// MACRO to access a value with a matrix.
+#define MATRIX_VALUE_PTR( pA, row, col )  (&(((pA)->pContents)[ (row * (pA)->cols) + col]))
+
+
+//------------------------------------------------
+// Private Function Prototypes
+//------------------------------------------------
+
+static matrix_t *   createMatrix( int rows, int cols );
+static void         destroyMatrix( matrix_t *pMat );
+static matrix_t *   createTranspose( matrix_t *pMat );
+static matrix_t *   createProduct( matrix_t *pLeft, matrix_t *pRight );
+
+
+//=========================================================
+//      Global function definitions
+//=========================================================
+
+
+//--------------------------------------------------------
+// polyfit()
+// Computes polynomial coefficients that best fit a set
+// of input points.
+//
+// The degree of the fitted polynomial is one less than
+// the count of elements in the polynomial vector.
+//
+// Uses matrix algebra of the form:
+//              A * x = b
+// To solve the MLS equation:
+//              (AT) * A * x = (AT) * b
+// where (AT) is the transpose of A.
+//
+// If the n+1 input points are {(x0, y0), (x1, y1), ... (xn, yn)},
+// then the i'th row of A is: {(xi)^0, (xi)^1, ... (xn)^n},
+// and the i'th row of b is: {yi}.
+//
+// Returns   0 if success, 
+//          -1 if passed a NULL pointer,
+//          -2 if (pointCount < coefficientCount),
+//          -3 if unable to allocate memory,
+//          -4 if unable to solve equations.
+//--------------------------------------------------------
+//int polyfit( int pointCount, point_t pointArray[],  int coeffCount, double coeffArray[] )
+int Polyfit::polyfit( int pointCount, double *xValues, double *yValues, int coefficientCount, double *coefficientResults )
+{
+    int rVal = 0;
+    int degree = coefficientCount - 1;
+
+    // Check that the input pointers aren't null.
+    if( (NULL == xValues) || (NULL == yValues) || (NULL == coefficientResults) )
+    {
+        return -1;
+    }
+    // Check that pointCount >= coefficientCount.
+    if(pointCount < coefficientCount)
+    {
+        return -2;
+    }
+
+    // Make the A matrix:
+    matrix_t *pMatA = createMatrix( pointCount, coefficientCount );
+    if( NULL == pMatA)
+    {
+        return -3;
+    }
+
+    for( int r = 0; r < pointCount; r++)
+    {
+        for( int c = 0; c < coefficientCount; c++)
+        {
+            *(MATRIX_VALUE_PTR(pMatA, r, c)) = powl((xValues[r]), (double) (degree -c));
+        }
+    }
+
+    // Make the b matrix
+    matrix_t *pMatB = createMatrix( pointCount, 1);
+    if( NULL == pMatB )
+    {
+        return -3;
+    }
+
+    for( int r = 0; r < pointCount; r++)
+    {
+        *(MATRIX_VALUE_PTR(pMatB, r, 0)) = yValues[r];
+    }
+
+    // Make the transpose of matrix A
+    matrix_t * pMatAT = createTranspose( pMatA );
+    if( NULL == pMatAT )
+    {
+        return -3;
+    }
+
+    // Make the product of matrices AT and A:
+    matrix_t *pMatATA = createProduct( pMatAT, pMatA );
+    if( NULL == pMatATA )
+    {
+        return -3;
+    }
+
+    // Make the product of matrices AT and b:
+    matrix_t *pMatATB = createProduct( pMatAT, pMatB );
+    if( NULL == pMatATB )
+    {
+        return -3;
+    }
+
+    // Now we need to solve the system of linear equations,
+    // (AT)Ax = (AT)b for "x", the coefficients of the polynomial.
+
+    for( int c = 0; c < pMatATA->cols; c++ )
+    {
+        int pr = c;     // pr is the pivot row.
+        double prVal = *MATRIX_VALUE_PTR(pMatATA, pr, c);
+        // If it's zero, we can't solve the equations.
+        if( 0.0 == prVal )
+        {
+            // printf( "Unable to solve equations, pr = %d, c = %d.\n", pr, c );
+            rVal = -4;
+            break;
+        }
+        for( int r = 0; r < pMatATA->rows; r++)
+        {
+            if( r != pr )
+            {
+                double targetRowVal = *MATRIX_VALUE_PTR(pMatATA, r, c);
+                double factor = targetRowVal / prVal;
+                for( int c2 = 0; c2 < pMatATA->cols; c2++ )
+                {
+                    *MATRIX_VALUE_PTR(pMatATA, r, c2) -=  *MATRIX_VALUE_PTR(pMatATA, pr, c2) * factor; 
+                    // printf( "c = %d, pr = %d, r = %d, c2=%d, targetRowVal = %f, prVal = %f, factor = %f.\n",
+                    //         c, pr, r, c2, targetRowVal, prVal, factor );
+
+                    // showMatrix( pMatATA );
+                   
+                }
+                *MATRIX_VALUE_PTR(pMatATB, r, 0) -=  *MATRIX_VALUE_PTR(pMatATB, pr, 0) * factor;
+            }
+        }
+    }
+    for( int c = 0; c < pMatATA->cols; c++ )
+    {
+        int pr = c;
+        // now, pr is the pivot row.
+        double prVal = *MATRIX_VALUE_PTR(pMatATA, pr, c);
+        *MATRIX_VALUE_PTR(pMatATA, pr, c) /= prVal;
+        *MATRIX_VALUE_PTR(pMatATB, pr, 0) /= prVal;
+    }
+
+    for( int i = 0; i < coefficientCount; i++)
+    {
+        coefficientResults[i] = *MATRIX_VALUE_PTR(pMatATB, i, 0);
+    }
+
+    
+    destroyMatrix( pMatATB );
+    destroyMatrix( pMatATA );
+    destroyMatrix( pMatAT );
+
+    destroyMatrix( pMatA );
+    destroyMatrix( pMatB );
+    return rVal;
+}
+
+
+//=========================================================
+//      Private function definitions
+//=========================================================
+
+
+//--------------------------------------------------------
+// createTranspose()
+// Returns the transpose of a matrix, or NULL.
+//
+// The caller must free both the allocated matrix
+// and its contents array.
+//--------------------------------------------------------
+static matrix_t * createTranspose( matrix_t *pMat )
+{
+    matrix_t *rVal = (matrix_t *) calloc(1, sizeof(matrix_t));
+    rVal->pContents = (double *) calloc( pMat->rows * pMat->cols, sizeof( double ));
+    rVal->cols = pMat->rows;
+    rVal->rows = pMat->cols;
+    for( int r = 0; r < rVal->rows; r++ )
+    {
+        for( int c = 0; c < rVal->cols; c++ )
+        {
+            *MATRIX_VALUE_PTR(rVal, r, c) = *MATRIX_VALUE_PTR(pMat, c, r);
+        }
+    }
+    return rVal;
+}
+
+//--------------------------------------------------------
+// createProduct()
+// Returns the product of two matrices, or NULL.
+//
+// The caller must free both the allocated product matrix
+// and its contents array.
+//--------------------------------------------------------
+static matrix_t * createProduct( matrix_t *pLeft, matrix_t *pRight )
+{
+    matrix_t *rVal = NULL;
+    if( (NULL == pLeft) || (NULL == pRight) || (pLeft->cols != pRight->rows) )
+    {
+        printf( "Illegal parameter passed to createProduct().\n");
+    }
+    else
+    {
+        // Allocate the product matrix.
+        rVal = (matrix_t *) calloc(1, sizeof(matrix_t));
+        rVal->rows = pLeft->rows;
+        rVal->cols = pRight->cols;
+        rVal->pContents = (double *) calloc( rVal->rows * rVal->cols, sizeof( double ));
+
+        // Initialize the product matrix contents:
+        // product[i,j] = sum{k = 0 .. (pLeft->cols - 1)} (pLeft[i,k] * pRight[ k, j])
+        for( int i = 0; i < rVal->rows; i++)
+        {
+            for( int j = 0; j < rVal->cols; j++ )
+            {
+                for( int k = 0; k < pLeft->cols; k++)
+                {
+                    *MATRIX_VALUE_PTR(rVal, i, j) +=
+                        (*MATRIX_VALUE_PTR(pLeft, i, k)) * (*MATRIX_VALUE_PTR(pRight, k, j));
+                }
+            }
+        }
+    }    
+       
+    return rVal;
+}
+
+//--------------------------------------------------------
+// destroyMatrix()
+// Frees both the allocated matrix and its contents array.
+//--------------------------------------------------------
+static void destroyMatrix( matrix_t *pMat )
+{
+    if(NULL != pMat)
+    {
+        if(NULL != pMat->pContents)
+        {
+            free(pMat->pContents);
+        }
+        free( pMat );
+    }
+}
+
+//--------------------------------------------------------
+// createMatrix()
+// Allocates the matrix and clears its contents array.
+//--------------------------------------------------------
+static matrix_t *createMatrix( int rows, int cols )
+{
+    matrix_t *rVal = (matrix_t *) calloc(1, sizeof(matrix_t));
+    if(NULL != rVal)
+    {
+        rVal->rows = rows;
+        rVal->cols = cols;
+        rVal->pContents = (double *) calloc( rows * cols, sizeof( double ));
+        if(NULL == rVal->pContents)
+        {
+            free( rVal );
+            rVal = NULL;
+        }
+    }
+
+    return rVal;
+}
+
+ 
diff -r fa07b6c6238a -r 7f2ec2bc9d2e src/polyfit.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/polyfit.h	Sat Oct 14 18:50:47 2023 +0200
@@ -0,0 +1,58 @@
+/**
+ * @brief Header file for MLS polynomial fitting.
+ * @file polyfit.h
+ * @author Henry Forson, Melbourne, FL
+ */
+
+
+//------------------------------------------------------------------------------------
+// MIT License
+//
+// Copyright (c) 2020 Henry M. Forson
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+//------------------------------------------------------------------------------------
+
+
+#ifndef POLYFIT_H
+#define POLYFIT_H
+
+#include <QString>
+
+
+
+/**
+ * @namespace Polyfit
+ *
+ * @brief Global math functions.
+ */
+namespace Polyfit {
+    /**
+     * @brief Computes polynomial coefficients that best fit a set of input points.
+     * @param pointCount Number of points
+     * @param xValues Array of double values.
+     * @param yValues Array of double values.
+     * @param coefficientCount Number of coefficients in results.
+     * @param coefficientResults Array of coefficientCount double results.
+     * @return Error result, 0 is Ok.
+     */
+    int polyfit( int pointCount, double *xValues, double *yValues, int coefficientCount, double *coefficientResults );
+}
+
+#endif	// POLYFIT_H