--- loncom/homework/functionplotresponse.pm	2011/11/19 23:35:25	1.77
+++ loncom/homework/functionplotresponse.pm	2011/11/20 00:34:52	1.78
@@ -1,7 +1,7 @@
 # LearningOnline Network with CAPA
 # Functionplot responses
 #
-# $Id: functionplotresponse.pm,v 1.77 2011/11/19 23:35:25 www Exp $
+# $Id: functionplotresponse.pm,v 1.78 2011/11/20 00:34:52 www Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -1388,6 +1388,9 @@ sub objectcoords {
  
 sub vectorangle {
    my ($x,$y)=@_;
+   my $angle=57.2957795*atan2($y,$x);
+   if ($angle<0) { $angle=360+$angle; }
+   return $angle;
 }
 
 sub vectorlength {
@@ -1395,6 +1398,19 @@ sub vectorlength {
    return sqrt($x*$x+$y*$y);
 }
 
+sub relvector {
+   my ($xs,$xe,$ys,$ye)=@_;
+   return ($xe-$xs,$ye-$ys);
+}
+
+sub plotvectorlength {
+   return &vectorlength(&relvector(&vectorcoords(@_)));
+}
+
+sub plotvectorangle {
+   return &vectorangle(&relvector(&vectorcoords(@_)));
+}
+
 
 #
 # Evaluate a functionplotvectorrule
@@ -1402,6 +1418,7 @@ sub vectorlength {
 
 sub functionplotvectorrulecheck {
    my ($rule,$xmin,$xmax,$ymin,$ymax,$safeeval)=@_;
+   &addlog("=================");
    my ($label,$type)=split(/\:/,$rule);
    if ($type eq 'vector') {
       return &vectorcheck($rule,$xmin,$xmax,$ymin,$ymax,$safeeval);
@@ -1416,11 +1433,14 @@ sub vectorcheck {
        $attachpoint,$notattachpoint,
        $tailpoint,$tippoint,$nottailpoint,$nottippoint,
        $length,$angle,$lengthpercenterror,$anglepercenterror)=split(/\:/,$rule);
+   &addlog("Vector Rule $label for vector ".$vector);
+
 }
 
 sub sumcheck {
    my ($rule,$xmin,$xmax,$ymin,$ymax,$safeeval)=@_;
    my ($label,$type,$id,$object,$length,$angle,$lengthpercenterror,$lengthabserror,$anglepercenterror)=split(/\:/,$rule);
+   &addlog("Vector Sum Rule $label for vectors attached to ".$object);
 }
 
 #