Re: oct file: multiply a matrix by a vector

[David Bateman]

To reduce the number of cache misses you should traverse the matrix in 
the way it is stored in memory. Octave uses Fortran conventions for the 
storage and so you should reverse the for loops like

for (int j=0; j<mat1.cols(); j++)
 {
     double val = mat2(j)
     for (int i=0; i<mat1.rows(); i++)
       mat1(i,j) /= val;
 }

this should give you a significant speed increase...

D.

--
David Bateman                                address@hidden
Motorola Labs - Paris                        +33 1 69 35 48 04 (Ph) 
Parc Les Algorithmes, Commune de St Aubin    +33 1 69 35 77 01 (Fax) 
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