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;
}