Fix pinv bug with 0 values introduced in cset 16b0cd465ecd. * pinv.cc (Fpinv): Add %!tests for diagonal matrices * CDiagMatrix.cc (pseudo_inverse), dDiagMatrix.cc (pseudo_inverse), fCDiagMatrix.cc (pseudo_inverse), fDiagMatrix.cc (pseudo_inverse): Don't skip assigning 0 to retval element when matrix element is 0 since retval memory is not initialized to 0.

#include <iostream>
#include <octave/oct.h>

int
main (void)
{
  std::cout << "Hello Octave world!\n";

  int n = 2;
  Matrix a_matrix = Matrix (n, n);

  for (octave_idx_type i = 0; i < n; i++)
    for (octave_idx_type j = 0; j < n; j++)
      a_matrix(i,j) = (i + 1) * 10 + (j + 1);

  std::cout << a_matrix;

  return 0;
}