Now, part of the "win" of writing everything that you possibly can in Perl, is that you end up with C interfaces that can be more efficient. You mentioned in chatter that your matrix is rather large. So, let's say that you want to use this C code on the same (or similar) matrix more than once. Then you might want to use something like this: 

sub PackMatrix {
    my $avMatrix= shift(@_);
    my $nRows= 0 + @$avMatrix;
    my $nCols= 0 + @{ $avMatrix->[0] };
    my $ptrSize= length(pack"p","");
    my $ptrLen= $ptrSize*$nRows;
    my $rowLen= length(pack"f",0)*$nCols;
    my $dataLen= $rowLen*$nRows;
    my $packedMatrix;
    if(  pack("p",$packedMatrix) != pack("I",0+\$packedMatrix)  ) {
        die "This platform has strange pointers!";
    }
    length($packedMatrix)= $ptrLen + $dataLen;
    $packedMatrix= "\0" x $ptrLen;
    for my $avRow (  @$avMatrix  ) {
        die "Row has ",0+@$avRow," entries instead of $width!"
            unless  $width == 0+@$avRow;
        $packedMatrix .= pack("f$width",@$avRow);
    }
    my $ptr= $ptrLen + \$packedMatrix;
    for my $i (  0..$#$avMatrix  ) {
        substr( $packedMatrix, $i*$ptrSize, $ptrSize )=
            pack "I", $ptr;
        $ptr += $rowLen;
    }
    return \$packedMatrix;
}

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Then you can pass this single string around (always by reference, never by value) and use it again and again. Sorry, I have to run now so I don't have time to explain this in detail. Feel free to ask questions. (:

        - tye (but my friends call me "Tye")

In reply to (tye)Re4: Passing References to Arrays into Perl Extensions in C by tye
in thread Passing References to Arrays into Perl Extensions in C by Evanovich

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