Next: Summary Up: Matrix representation of loop transformations Previous: Example: loop given earlier

...

We can also represent loop interchange by a matrix transformation.

After transforming the skewed loop by matrix ${\bf V}=\left[ \begin{array}{cc}
0 & 1 \\
1 & 0
\end{array} \right] $ (i.e. loop interchange) we get:

1.
Distance: (1,1), direction: (<,<)
2.
Distance: (1,0), direction: (<,.)
The transformed iteration space is the transpose of the skewed iteration space:
S00            
S10 S11          
S20 S21 S22        
S30 S31 S32 S33      
  S41 S42 S43      
    S52 S53      
      S63