OK, I am still kind of new to all of this, and I have looked in a book that I have to try to help me, but my code for a program is getting to be enormous. I would like to shrink it by creating subroutines. I would also like to know how to use them and how to give the subroutine variables to use and have them return others. Here is an example of code that I would like to turn into a subroutine.

{
$xachange = ($blocks[$blockcount][$icount][1] - $datapoint[($blocks[$b
+lockcount][$icount][5])][1]);
            $xbchange = (($datapoint[($blocks[$blockcount][$icount][5]
+)][1]) - ($blocks[$blockcount][($icount + 1)][1]));
            $yachange = ($blocks[$blockcount][$icount][2] - $datapoint
+[($blocks[$blockcount][$icount][5])][2]);
            $ybchange = (($datapoint[($blocks[$blockcount][$icount][5]
+)][2]) - ($blocks[$blockcount][($icount + 1)][2]));
            $da = sqrt(($xachange*$xachange) + ($yachange*$yachange));
            $db = sqrt(($xbchange*$xbchange) + ($ybchange*$ybchange));
            $nxa = (($blocks[$blockcount][$icount][1] + ($xachange/$da
+)*$radius));
            $nya = (($blocks[$blockcount][$icount][2] + ($yachange/$da
+)*$radius));
            $nxb = (($blocks[$blockcount][$icount][1] + ($xbchange/$db
+)*$radius));
            $nyb = (($blocks[$blockcount][$icount][2] + ($ybchange/$db
+)*$radius));
            $gxa1 = $nxa / 25.4;
            $gya1 = $nya / 25.4;
            $gxb1 = $nxb / 25.4;
            $gyb1 = $nyb / 25.4;
            $gpx = $datapoint[($blocks[$blockcount][$icount][5])][1] /
+ 25.4;
            $gpy = $datapoint[($blocks[$blockcount][$icount][5])][2] /
+ 25.4;
            select JOB;
            printf "G01X%.3fY%.3f\n", $gxa1, $gya1;
            printf "G03X%.3fY%.3fI%.3fJ%.3f\n", $gxb1, $gyb1, $gpx, $g
+py;
            select STDOUT;
            print " 1 [4] G033333333333333333 $blockcount, $icount, 1 
+\n";
            $blocks[$blockcount][$icount][3] = 1;
            $icount = $icount + 1;
}
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Any help would be greatly appreciated, even a small subroutine, where I have to give it global variables, it uses them by naming them different local variables and does calculations, then gives return variables. Thanks