What does BLAS DGEMV error code -6 mean?

StackOverflow https://stackoverflow.com/questions/3056964

  •  27-09-2019
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Question

I have a program that runs through R but uses the BLAS routines. It runs through correctly about 8 times but then throws an error:

BLAS/LAPACK routine 'DGEMV ' gave error code -6

What does this error code mean?

Was it helpful?

Solution

R defines the XERBLA function as

void F77_NAME(xerbla)(const char *srname, int *info)
{
   /* srname is not null-terminated.  It should be 6 characters. */
    char buf[7];
    strncpy(buf, srname, 6);
    buf[6] = '\0';
    error(_("BLAS/LAPACK routine '%6s' gave error code %d"), buf, -(*info));
}

from the src/main/print.c file.

the Netlib version of dgemv.f shows that only the input parameters are checked. A code of 6 shows a problem with either the LDA or M parameter.

*...
  ELSE IF (LDA.LT.MAX(1,M)) THEN
      INFO = 6
*...
  END IF
  IF (INFO.NE.0) THEN
      CALL XERBLA('DGEMV ',INFO)
      RETURN

So it appears that R takes the negative of the BLAS error code, which I think causes lots of confusion. I think this answers my question but not my problem, since it works several times with the same parameters before the error is thrown.

OTHER TIPS

DGEMV does not return any error codes.

This bug implies that the error is coming from R itself.

Perhaps you should file a bug against R.

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