MxSetBlock question

[empottasch]

hi, I am working with the matrix that is returned from the PriceVolumeDistribution

I extract the volume and price from the matrix using:

rows = MxGetSize( mxVolb, 0 );
volb = MxGetBlock( mxVolb, 0, rows - 1, 1, 1, True );
prcb = MxGetBlock( mxVolb, 0, rows - 1, 0, 0, True );

then I create a second matrix in wich I want to keep the price column (column 0 ) but store something else in column 1

so I create the matrix:

mxVolb_imb = Matrix( rows, 2, 0 );

then I want to put the price array back in column 0 of the newly created matrix. I use:

MxSetBlock( mxVolb_imb, 0, rows - 1, 0, 0, prcb );

but I get zeros. I know the prcb array is filled correctly because this works:

            for( xx = 0; xx < rows - 1; xx++ )
            {
                mxVolb_imb[xx][0] = prcb[xx];
            }

why does

MxSetBlock( mxVolb_imb, 0, rows - 1, 0, 0, prcb );

not work? Thanks

[Tomasz]

By default all arguments are passed by value (which means that arguments are not modified by function). Therefore
MxSetBlock RETURNS modified matrix, so you have to do ASSIGNMENT:

// must assign result
mxVolb_imb = MxSetBlock( mxVolb_imb, 0, rows - 1, 0, 0, prcb );

By the way in the guide AFL Function Reference - MXSETBLOCK there is a note:

Note: the function creates new matrix as a result (so source matrix is unaffected unless you do the assignment of the result back to the original variable)

[empottasch]

thank you, will try that