Re: oct file: multiply a matrix by a vector

[Robert A. Macy]

Will that be faster than...

function matout=elementdivide(mat1,mat2);
%  proper checks
[rowsmat1,columnsmat1]=size(mat1);
matout=mat1./(ones(rowsmat1,1)*mat2);

...?

     - Robert -

On Sat, 02 Jul 2005 12:32:57 -0400
 Brian Blais <address@hidden> wrote:
> Hello,
> 
> I was wondering if there is a more efficient way of doing
> the following
> in an oct file.  Many times I want to have a matrix
> multiplied by a
> vector, in a way that each row of the matrix is
> element-by-element
> multiplied by the vector.  I wrote the following,
> straightforward, code
> for it but was wondering if there is a more advised way
> of doing it.  My
> primary interest is in speed, but there may be other
> reasons to not do
> it the way I have written.
> 
>               thanks,
> 
>                       Brian Blais
> 
> int rquotient(Matrix &mat1,Matrix &mat2) {
> 
>    Matrix retval;
> 
>    if (mat1.cols()!=mat2.cols()) {
>      error("Size mismatch");
>      return(1);
>    }
> 
>    for (int i=0; i<mat1.rows(); i++) {
>      for (int j=0; j<mat1.cols(); j++) {
>        mat1(i,j)/=mat2(j);
>      }
> 
>    }
> 
> 
>    return(0);
> 
> }
> 
> -- 
> -----------------
> 
>              address@hidden
>              http://web.bryant.edu/~bblais
> 



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