So Below is my program in its entirety. The clock() functions are giving me some very strange results. I compile it in gcc on a unix box. the clock() function at first(line 167) I print start time immediately after declaring it and the result is an incredibly long number that just cant be right.
second, after I print the result(line 191) both the endTime Variable and just printing clock() results in it equaling the value of the variable A.
now more fun, if I move that print statement at line 191 where i print the result below where I print clock(), both clock() and endtime prints as 0.
I'm very confusd and have been tinkering and asking folks for help for several hours. anyone here have any ideas?
Code:/*///////////////////////////////////////////////////////////////////////////// // Linear Curve Fitting - This program fits a line to the data points in the // file provided on the command line (one data point per line of text in the // file). //////////////////////////////////////////////////////////////////////////////*/ #include <stdio.h> #include <stdlib.h> #include "data.h" //#include <string.h> #include <time.h> ////////////////////////////////////////////////////////////////////////////// // Class declaration for determining the "best" line for a given set of X-Y // data points. ////////////////////////////////////////////////////////////////////////////// // X data list double* Data_X; // Y data list double* Data_Y; /*The length of the list*/ int Data_len = 0; /*The number of elements in the lists*/ int Data_elems = 0; clock_t startTime,endTime; // The constant 'B' double B; // The coefficient to the linear term 'A' double A; // Flag indicating that the coefficients have been computed int CoefficientsComputed; /*///////////////////////////////////////////////////////////////////////////// // AddPoint() - Accepts a single point and adds it to the Array, Resizing if necessary /////////////////////////////////////////////////////////////////////////////*/ void AddPoint(double X, double Y) { /*If the array memmory has not been allocated, Data_len will be 0, so allocate and insert first elements*/ if (Data_len == 0){ Data_X = (double*)malloc(sizeof(double)* 3); Data_Y = (double*)malloc(sizeof(double)* 3); Data_X[0] = X; Data_Y[0] = Y; Data_len = 3; Data_elems = 1; } /*if*/ /*if the number of elements = the size of the array, double the size of the array*/ else if(Data_len == Data_elems){ Data_len *= 2; Data_X = realloc(Data_X, (sizeof(double) * Data_len)); Data_Y = realloc(Data_Y, (sizeof(double) * Data_len)); /*add the X and Y to their respective arrays and increment the counter*/ Data_X[Data_elems] = X; Data_Y[Data_elems] = Y; Data_elems++; } /*Add the elements to the array and increment the elemnt variable.*/ else{ Data_X[Data_elems] = X; Data_Y[Data_elems] = Y; Data_elems++; } } // AddPoint() /*///////////////////////////////////////////////////////////////////////////// // GetNumberOfPoints() - Returns the number of points collected /////////////////////////////////////////////////////////////////////////////*/ int GetNumberOfPoints() { return Data_elems; } // GetNumberOfPoints() /*///////////////////////////////////////////////////////////////////////////// // ComputeCoefficients() - Calculate the value of the linear coefficient // 'A' and the constant term 'B' in Y = A * X + B /////////////////////////////////////////////////////////////////////////////*/ void ComputeCoefficients() { // Declare and initialize sum variables double S_XX = 0.0; double S_XY = 0.0; double S_X = 0.0; double S_Y = 0.0; // Iterators // Compute the sums int lcv_X = 0; while (lcv_X <= Data_elems) { S_XX += (Data_X[lcv_X]) * (Data_X[lcv_X]); S_XY += (Data_X[lcv_X]) * (Data_Y[lcv_X]); S_X += (Data_X[lcv_X]); S_Y += (Data_Y[lcv_X]); // Iterate lcv_X++; } // while() // Compute the constant B = (((S_XX * S_Y) - (S_XY * S_X)) / ((Data_elems * S_XX) - (S_X * S_X))); // Compute the linear coefficient A = (((Data_elems * S_XY) - (S_X * S_Y)) / ((Data_elems * S_XX) - (S_X * S_X))); // Indicate that the Coefficients have been computed CoefficientsComputed = 1; } // ComputeCoefficients() ////////////////////////////////////////////////////////////////////////////// // GetConstant() - Calculate the value of the constant 'B' in Y = A * X + B ////////////////////////////////////////////////////////////////////////////// double GetConstant(void) { if (CoefficientsComputed == 0) { ComputeCoefficients(); } // if() return B; } // GetConstant() ////////////////////////////////////////////////////////////////////////////// // GetLinearCoefficient() - Calculate the value of the linear coefficient // 'A' in Y = A * X + B ////////////////////////////////////////////////////////////////////////////// double GetLinearCoefficient(void) { if (CoefficientsComputed == 0) { ComputeCoefficients(); } // if() return A; } // GetLinearCoefficient() ////////////////////////////////////////////////////////////////////////////// // Main program to fit a line to the data. ////////////////////////////////////////////////////////////////////////////// int main(int argc, char *argv[]) { // Check that a command line argument was provided //printf("%i", argc); if (argc == 2) { CoefficientsComputed = 0; // Variables to hold the constant and linear coefficients of the line //double A, B; //temp variable to find location of tab and split the string //char * pch; //element that the tab char is int tabLoc; double X, Y; // Temporary variables to hold data read from file char temp1[sizeof(double) *3]; //start and end times //int a; FILE *inputFile; startTime = clock(); //(void) time(&startTime); printf("%f\n",startTime); inputFile = fopen(argv[1],"r"); ///printf("%iWOO\n", 1); //a = fscanf(inputFile, "%f\t%f", X,Y); // While a data point is returned, add it to the list while (fgets(temp1,1000,inputFile) != NULL) { sscanf(temp1,"%lf %lf",&X,&Y); //pch = strchr(temp1," "); //tabLoc = pch; //- temp1 + 1; // printf(temp1); //printf("\n"); // Add the data point AddPoint(X, Y); //a = } /* while() */ // Save the constant value and the linear coefficent A = GetLinearCoefficient(); B = GetConstant(); // Print out the line that fits the data set. endTime = clock(); printf( "The line is: Y = %.4f * X + %.4f\n" ,A, B ); printf("%fEND\n",endTime); printf("%fstart\n",clock()); printf("%f\n",(double)CLOCKS_PER_SEC); printf("%f\n",(double)GetNumberOfPoints()); printf( "Time per calculation = %.30f mSec", ((double)(endTime) / (double)CLOCKS_PER_SEC / (double)GetNumberOfPoints()) * 1000.0); } // if() else { // Display program usage information printf( "Usage: %s <filename>",argv[0]); } // if...else() return(0); } // main()
Originally Posted by somekid413
