From bug-octave-request at bevo dot che dot wisc dot edu  Tue Jan 19 01:22:40 1999
Subject: Multiplication of ColumnVector by RowVector in liboctave gets an error.
From: Samsung Lim <slim at inha dot ac dot kr>
To: bug-octave at bevo dot che dot wisc dot edu
Date: Tue, 19 Jan 1999 16:20:28 +0900

Bug report for Octave 2.0.13 configured for sparc-sun-solaris2.5.1

Description:
-----------

 When the liboctave library is used, the muliplication of a
 column vector by a row vector gets an error unless two vectors have
 the same dimensions. (Of course, it doesn't happen in octave,
 though). I think this is due to the definition of the
 multiplication in the "liboctave/dMatrix.cc". The following is the
 original source code. It checks if "len != a_len", but why?

### BEGIN CODE ###
// column vector by row vector -> matrix operations

Matrix
operator * (const ColumnVector& v, const RowVector& a)
{
  Matrix retval;

  int len = v.length ();
  int a_len = a.length ();

  if (len != a_len)
 gripe_nonconformant ("operator *", len, 1, 1, a_len);
  else
 {
   if (len != 0)
  {
    retval.resize (len, a_len);
    double *c = retval.fortran_vec ();

    F77_XFCN (dgemm, DGEMM, ("N", "N", len, a_len, 1, 1.0,
           v.data (), len, a.data (), 1, 0.0,
           c, len, 1L, 1L));

    if (f77_exception_encountered)
   (*current_liboctave_error_handler)
     ("unrecoverable error in dgemm");
  }
 }

  return retval;
}
### END CODE ###

Fix:
---

 Why not "len != a_len"? Shouldn't it be fixed like this?

### BEGIN CODE ###
// column vector by row vector -> matrix operations

Matrix
operator * (const ColumnVector& v, const RowVector& a)
{
  Matrix retval;

  int len = v.length ();
  int a_len = a.length ();

  if (len != 0)
 {
   retval.resize (len, a_len);
   double *c = retval.fortran_vec ();

   F77_XFCN (dgemm, DGEMM, ("N", "N", len, a_len, 1, 1.0,
          v.data (), len, a.data (), 1, 0.0,
          c, len, 1L, 1L));

   if (f77_exception_encountered)
  (*current_liboctave_error_handler)
    ("unrecoverable error in dgemm");
 }

  return retval;
}
### END CODE ###