mirror of https://github.com/TheAlgorithms/C
81 lines
1.9 KiB
C
81 lines
1.9 KiB
C
/**
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* @file
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* \brief Program to compute the [QR
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* decomposition](https://en.wikipedia.org/wiki/QR_decomposition) of a given
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* matrix.
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* \author [Krishna Vedala](https://github.com/kvedala)
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*/
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#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <time.h>
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#include "qr_decompose.h"
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/**
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* main function
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*/
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int main(void)
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{
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double **A;
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unsigned int ROWS, COLUMNS;
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printf("Enter the number of rows and columns: ");
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scanf("%u %u", &ROWS, &COLUMNS);
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if (ROWS < COLUMNS)
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{
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fprintf(stderr,
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"Number of rows must be greater than or equal to "
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"number of columns.\n");
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return -1;
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}
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printf("Enter matrix elements row-wise:\n");
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A = (double **)malloc(ROWS * sizeof(double *));
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for (int i = 0; i < ROWS; i++)
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A[i] = (double *)malloc(COLUMNS * sizeof(double));
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for (int i = 0; i < ROWS; i++)
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for (int j = 0; j < COLUMNS; j++) scanf("%lf", &A[i][j]);
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print_matrix(A, ROWS, COLUMNS);
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double **R = (double **)malloc(sizeof(double *) * ROWS);
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double **Q = (double **)malloc(sizeof(double *) * ROWS);
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if (!Q || !R)
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{
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perror("Unable to allocate memory for Q & R!");
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return -1;
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}
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for (int i = 0; i < ROWS; i++)
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{
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R[i] = (double *)malloc(sizeof(double) * COLUMNS);
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Q[i] = (double *)malloc(sizeof(double) * ROWS);
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if (!Q[i] || !R[i])
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{
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perror("Unable to allocate memory for Q & R.");
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return -1;
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}
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}
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clock_t t1 = clock();
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qr_decompose(A, Q, R, ROWS, COLUMNS);
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double dtime = (double)(clock() - t1) / CLOCKS_PER_SEC;
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print_matrix(R, ROWS, COLUMNS);
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print_matrix(Q, ROWS, COLUMNS);
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printf("Time taken to compute: %.4g sec\n", dtime);
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for (int i = 0; i < ROWS; i++)
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{
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free(A[i]);
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free(R[i]);
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free(Q[i]);
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}
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free(A);
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free(R);
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free(Q);
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return 0;
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}
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