From bug-octave-request at bevo dot che dot wisc dot edu  Tue Oct 31 14:09:22 2000
Subject: vector transpose 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: Tue, 31 Oct 2000 14:09:02 -0600

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: vector transpose speedup
| 
| Bug report for Octave 2.1.31 configured for %OCTAVE_CANONICAL_HOST_TYPE%
| 
| Description:
| -----------
| 
| x' does not need to copy the matrix if it is nx1 or 1xn
| 
| Repeat-By:
| ---------
| 
| Fix:
| ---
| 
| *** Array2.cc	2000/10/05 09:33:32	1.1
| --- Array2.cc	2000/10/04 19:17:18
| ***************
| *** 220,233 ****
|   Array2<T>
|   Array2<T>::transpose (void) const
|   {
| -   Array2<T> result (d2, d1);
|   
| !   if (d1 > 0 && d2 > 0)
| !     for (int j = 0; j < d2; j++)
| !       for (int i = 0; i < d1; i++)
| ! 	result.elem (j, i) = elem (i, j);
|   
| !   return result;
|   }
|   
|   /*
| --- 220,241 ----
|   Array2<T>
|   Array2<T>::transpose (void) const
|   {
|   
| !   if (d1 > 1 && d2 > 1)
| !     {
| !       Array2<T> result (d2, d1);
|   
| !       for (int j = 0; j < d2; j++)
| ! 	for (int i = 0; i < d1; i++)
| ! 	  result.xelem (j, i) = xelem (i, j);
| ! 
| !       return result;
| !     }
| !   else
| !     {
| !       // Fast transpose for vectors and empty matrices
| !       return Array2<T> (*this, d2, d1);
| !     }
|   }
|   
|   /*

I applied this patch.

I left in both changes from elem to xelem, though it does not matter
for the RHS since they are the same for const objects.

jwe



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