example_DGESV_rowmajor.c File Reference

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <lapacke.h>
#include "lapacke_example_aux.h"

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Functions/Subroutines
int	main (int argc, char **argv)

Function/Subroutine Documentation

int main	(	int	argc,
		char **	argv
	)

Definition at line 41 of file example_DGESV_rowmajor.c.

                                {

        /* Locals */
        lapack_int n, nrhs, lda, ldb, info;
                int i, j;
                double normr, normb;
        /* Local arrays */
                double *A, *b, *Acopy, *bcopy;
                lapack_int *ipiv;
                
        /* Default Value */
            n = 5; nrhs = 1;

        /* Arguments */
            for( i = 1; i < argc; i++ ) {
                if( strcmp( argv[i], "-n" ) == 0 ) { 
                        n  = atoi(argv[i+1]);
                            i++;
                    }
                        if( strcmp( argv[i], "-nrhs" ) == 0 ) { 
                                nrhs  = atoi(argv[i+1]);
                                i++;
                        } 
                }
                
        /* Initialization */
        lda=n, ldb=nrhs;
                A = (double *)malloc(n*n*sizeof(double)) ;
                if (A==NULL){ printf("error of memory allocation\n"); exit(0); }
                b = (double *)malloc(n*nrhs*sizeof(double)) ;
                if (b==NULL){ printf("error of memory allocation\n"); exit(0); }
                ipiv = (lapack_int *)malloc(n*sizeof(lapack_int)) ;
                if (ipiv==NULL){ printf("error of memory allocation\n"); exit(0); }

        for( i = 0; i < n; i++ ) {
                for( j = 0; j < n; j++ ) A[i*lda+j] = ((double) rand()) / ((double) RAND_MAX) - 0.5;
                }

                for(i=0;i<n*nrhs;i++)
                        b[i] = ((double) rand()) / ((double) RAND_MAX) - 0.5;

        /* Print Entry Matrix */
        print_matrix_rowmajor( "Entry Matrix A", n, n, A, lda );
        /* Print Right Rand Side */
        print_matrix_rowmajor( "Right Rand Side b", n, nrhs, b, ldb );
        printf( "\n" );
        /* Executable statements */
        printf( "LAPACKE_dgesv (row-major, high-level) Example Program Results\n" );
        /* Solve the equations A*X = B */
        info = LAPACKE_dgesv( LAPACK_ROW_MAJOR, n, nrhs, A, lda, ipiv,
                        b, ldb );
        /* Check for the exact singularity */
        if( info > 0 ) {
                printf( "The diagonal element of the triangular factor of A,\n" );
                printf( "U(%i,%i) is zero, so that A is singular;\n", info, info );
                printf( "the solution could not be computed.\n" );
                exit( 1 );
        }
        if (info <0) exit( 1 );
        /* Print solution */
        print_matrix_rowmajor( "Solution", n, nrhs, b, ldb );
        /* Print details of LU factorization */
        print_matrix_rowmajor( "Details of LU factorization", n, n, A, lda );
        /* Print pivot indices */
        print_vector( "Pivot indices", n, ipiv );
        exit( 0 );
} /* End of LAPACKE_dgesv Example */

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