From bug-octave-request at che dot utexas dot edu  Sat Oct  9 21:54:11 1993
Subject: assignment bug with empty matrices
From: Karl Holmstrom <kalle at kyyppi dot kcl dot fi>
To: bug-octave at che dot utexas dot edu
Date: Sat, 09 Oct 1993 17:34:59 +0200


BUG DESCRIPTION:

 octave version 0.76 on HP-UX 8.07:

 The following assignments fail when A is not previously defined:
 A(1:2,:) = [1 2 3;4 5 6]
 A(:,1:3) = [1 2 3;4 5 6]
 Both operations are allowed in Matlab.

SAMPLE SESSION:

 kyyppi <17:27> <~>: octave
 Octave, version 0.76.  Copyright (C) 1992, 1993, John W. Eaton.
 This is free software with ABSOLUTELY NO WARRANTY.
 For details, type `warranty'.

 octave:1> A(1:2,:) = [1 2 3;4 5 6]
 error: A(range,:) = X: the number of rows in X must match the number of elements
  in range, and the number of columns in X must match the number of columns in A
 error: evaluating assignment expression near line 1, column 10
 octave:2> exit
 kyyppi <17:27> <~>:



POSSIBLE FIX: (two modifications in tc-assign.cc)

------  start of diff ------

*** tc-assign.cc.orig	Sat Oct  9 17:12:24 1993
--- tc-assign.cc	Sat Oct  9 17:12:42 1993
***************
*** 934,941 ****
      case magic_colon:
        {
  	int nc = columns ();
! 	if (! indexed_assign_conforms (ri.nelem (), nc, rhs_nr, rhs_nc))
  	  {
  	    error ("A(range,:) = X: the number of rows in X must match\
   the number of elements in range, and the number of columns in X must\
   match the number of columns in A");  
--- 934,955 ----
      case magic_colon:
        {
  	int nc = columns ();
! 	if (nc == 0 && rows () == 0)
  	  {
+ 	    if (rhs.is_complex_type ())
+ 	      {
+ 		complex_matrix = new ComplexMatrix ();
+ 		type_tag = complex_matrix_constant;
+ 	      }
+ 	    else
+ 	      {
+ 		matrix = new Matrix ();
+ 		type_tag = matrix_constant;
+ 	      }
+ 	    nc = rhs_nc;
+ 	  }
+ 	else if (! indexed_assign_conforms (ri.nelem (), nc, rhs_nr, rhs_nc))
+ 	  {
  	    error ("A(range,:) = X: the number of rows in X must match\
   the number of elements in range, and the number of columns in X must\
   match the number of columns in A");  
***************
*** 1023,1029 ****
        {
  	Range rj = tmp_j.range_value ();
  	int nr = rows ();
! 	if (! indexed_assign_conforms (nr, rj.nelem (), rhs_nr, rhs_nc))
  	  {
  	    error ("A(:,range) = X: the number of rows in X must match\
   the number of rows in A, and the number of columns in X must match\
--- 1037,1057 ----
        {
  	Range rj = tmp_j.range_value ();
  	int nr = rows ();
! 	if (columns() == 0 && nr == 0)
! 	  {
! 	    if (rhs.is_complex_type ())
! 	      {
! 		complex_matrix = new ComplexMatrix ();
! 		type_tag = complex_matrix_constant;
! 	      }
! 	    else
! 	      {
! 		matrix = new Matrix ();
! 		type_tag = matrix_constant;
! 	      }
! 	    nr = rhs_nr;
! 	  }
! 	else if (! indexed_assign_conforms (nr, rj.nelem (), rhs_nr, rhs_nc))
  	  {
  	    error ("A(:,range) = X: the number of rows in X must match\
   the number of rows in A, and the number of columns in X must match\

------  end of diff ------

 kalle