From bug-octave-request at bevo dot che dot wisc dot edu  Thu Oct 12 11:13:21 2000
Subject: magic colon speedup
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Paul Kienzle <pkienzle at kienzle dot powernet dot co dot uk>
Cc: bug-octave at bevo dot che dot wisc dot edu
Date: Thu, 12 Oct 2000 11:13:12 -0500

On  5-Oct-2000, Paul Kienzle <pkienzle at kienzle dot powernet dot co dot uk> wrote:

| To: bug-octave at bevo dot che dot wisc dot edu
| Cc: pkienzle
| Subject: magic colon speedup
| 
| Bug report for Octave 2.1.31 configured for %OCTAVE_CANONICAL_HOST_TYPE%
| 
| Description:
| -----------
| 
| x(:) makes an unnecessary copy of the matrix for size mxn, with m,n != 1

I made the changes below.  I did not apply your patch directly, since
it seems to undo some recent changes to the CVS sources.

jwe


Index: Array2-idx.h
===================================================================
RCS file: /usr/local/cvsroot/octave/liboctave/Array2-idx.h,v
retrieving revision 1.30
diff -c -r1.30 Array2-idx.h
*** Array2-idx.h	2000/10/10 23:41:20	1.30
--- Array2-idx.h	2000/10/12 16:12:09
***************
*** 66,73 ****
    int idx_orig_rows = idx_arg.orig_rows ();
    int idx_orig_columns = idx_arg.orig_columns ();
  
!   if (nr == 1 && nc == 1)
      {
        Array<T> tmp = Array<T>::index (idx_arg);
  
        if (tmp.length () != 0)
--- 66,82 ----
    int idx_orig_rows = idx_arg.orig_rows ();
    int idx_orig_columns = idx_arg.orig_columns ();
  
!   if (idx_arg.is_colon ())
      {
+       // Fast magic colon processing.
+ 
+       int result_nr = nr * nc;
+       int result_nc = result_nr ? 1 : 0;
+ 
+       retval = Array2<T> (*this, result_nr, result_nc);
+     }
+   else if (nr == 1 && nc == 1)
+     {
        Array<T> tmp = Array<T>::index (idx_arg);
  
        if (tmp.length () != 0)
***************
*** 77,83 ****
      }
    else if (nr == 1 || nc == 1)
      {
!       int result_is_column_vector = (nc == 1 || idx_arg.is_colon ());
  
        Array<T> tmp = Array<T>::index (idx_arg);
  
--- 86,92 ----
      }
    else if (nr == 1 || nc == 1)
      {
!       int result_is_column_vector = (nc == 1);
  
        Array<T> tmp = Array<T>::index (idx_arg);
  
***************
*** 94,100 ****
  	}
      }
    else if (liboctave_dfi_flag
- 	   || idx_arg.is_colon ()
  	   || (idx_arg.one_zero_only ()
  	       && idx_orig_rows == nr
  	       && idx_orig_columns == nc))
--- 103,108 ----
***************
*** 109,120 ****
  	  int result_nr = idx_orig_rows;
  	  int result_nc = idx_orig_columns;
  
! 	  if (idx_arg.is_colon ())
! 	    {
! 	      result_nr = nr * nc;
! 	      result_nc = result_nr ? 1 : 0;
! 	    }
! 	  else if (idx_arg.one_zero_only ())
  	    {
  	      result_nr = idx_arg.ones_count ();
  	      result_nc = (result_nr > 0 ? 1 : 0);
--- 117,123 ----
  	  int result_nr = idx_orig_rows;
  	  int result_nc = idx_orig_columns;
  
! 	  if (idx_arg.one_zero_only ())
  	    {
  	      result_nr = idx_arg.ones_count ();
  	      result_nc = (result_nr > 0 ? 1 : 0);



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