MKL dtrsv wrong output

Question

I am trying to properly use 'cblas_dtrsv' however I do not get right output and I do not know why. Here is my example(dtrsv_example.c)

#include <stdio.h>
#include <stdlib.h>
#include "mkl.h"

int main()
{
  double *A, *b, *x;
  int m, n, k, i, j;

  m = 4, k = 4, n = 4;

  printf (" Allocating memory for matrices aligned on 64-byte boundary for better \n"
      " performance \n\n");
  A = (double *)mkl_malloc( m*k*sizeof( double ), 64 );
  b = (double *)mkl_malloc( n*sizeof( double ), 64 );
  x = (double *)mkl_malloc( n*sizeof( double ), 64 );

  if (A == NULL || b == NULL || x == NULL) {
    printf( "\n ERROR: Can't allocate memory for matrices. Aborting... \n\n");
    mkl_free(A);
    mkl_free(b);
    mkl_free(x);
    return 1;
  }  
  A[0] = 11;
  for (i = 0; i < m; i++) {
    for (j = 0; j <= i; j++) {
      A[j + i*m] = (double)(j+i*m);
    }
  }
 for (i = 0; i < n; i++) {
    x[i] = (i+1)*5.0;
  }
  printf ("\n Computations completed.\n\n");

  printf ("\n Result x: \n");
  for (j = 0; j < n; j++) {
    printf ("%f\n", x[i]);
  }


  printf ("\n Deallocating memory \n\n");
  mkl_free(A);
  mkl_free(b);
  mkl_free(x);

  printf (" Example completed. \n\n");
  return 0;
}

Compilation seems fine:

icc -c -Wall   -c -o dtrsv_example.o dtrsv_example.c
icc dtrsv_example.o -o dtrsv_example -L/opt/intel/mkl/lib/intel64 -lmkl_intel_lp64 -lmkl_core -lmkl_sequential -lpthread -lm

However, I get the wrong result:

./dtrsv_example
Computations completed.


 Result x: 
0.000000
0.000000
0.000000
0.000000

 Deallocating memory 

 Example completed.

Any ideas of what I might be doing wrong here?

score 0 · Answer 1 · answered Jun 02 '14 at 12:29

Even though I thought I had carefully checked it, after a break I realized of my beginner mistake:

  for (j = 0; j < n; j++) {
    printf ("%f\n", x[i]);
  }

it should be x[j] instead! Hopefully other people can use my example to understand how the cblas_dtrsv interface is used.

MKL dtrsv wrong output

1 Answers1