--- loncom/homework/functionplotresponse.pm	2010/11/07 21:10:14	1.29
+++ loncom/homework/functionplotresponse.pm	2010/11/09 02:29:52	1.30
@@ -1,7 +1,7 @@
 # LearningOnline Network with CAPA
 # option list style responses
 #
-# $Id: functionplotresponse.pm,v 1.29 2010/11/07 21:10:14 www Exp $
+# $Id: functionplotresponse.pm,v 1.30 2010/11/09 02:29:52 www Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -398,11 +398,18 @@ sub start_functionplotrule {
              &Apache::edit::select_arg(&mt('Function:'),'derivative',
                                   [['0','Function itself'],
                                    ['1','First derivative'],
-                                   ['2','Second derivative']],$token).
+                                   ['2','Second derivative']],$token).' '.
+
              &Apache::edit::text_arg('(Initial) x-value:','xinitial',
-                                     $token,'4').' '.
-             &Apache::edit::text_arg('Final x-value for ranges:','xfinal',
-                                     $token,'4').' '.
+                                      $token,'4').
+             &Apache::edit::select_or_text_arg('(Initial) x-value label:','xinitiallabel',
+                                               [['start','Start of Plot']],$token,'8').' '.
+
+             &Apache::edit::text_arg('Optional final x-value for ranges:','xfinal',
+                                      $token,'4').
+             &Apache::edit::select_or_text_arg('Optional final x-value label:','xfinallabel',
+                                               [['end','End of Plot']],$token,'8').' '.
+
              &Apache::edit::select_arg(&mt('Relationship:'),'relationship',
                                   [['eq','equal'],
                                    ['ne','not equal'],
@@ -417,7 +424,7 @@ sub start_functionplotrule {
              &Apache::edit::end_row();
   } elsif ($target eq 'modified') {
     my $constructtag=&Apache::edit::get_new_args($token,$parstack,
-                                                 $safeeval,'index','derivative','xinitial','xfinal','relationship',
+                                                 $safeeval,'index','derivative','xinitial','xinitiallabel','xfinal','xfinallabel','relationship',
                                                            'value','percenterror');
     if ($constructtag) { $result=&Apache::edit::rebuild_tag($token); }
    }
@@ -616,7 +623,16 @@ sub populate_arrays {
                    if (defined($Apache::functionplotresponse::func[$xi])) { return 'no_func'; }
                    $xiold=$xi;
 # Function value
-                   $Apache::functionplotresponse::func[$xi]=&cubic_hermite($t,@yparms);
+                   my $funcval=&cubic_hermite($t,@yparms);
+                   $Apache::functionplotresponse::func[$xi]=$funcval;
+                   if (defined($funcval)) {
+                      if ($xi<$Apache::functionplotresponse::functionplotrulelabels{'start'}) {
+                         $Apache::functionplotresponse::functionplotrulelabels{'start'}=$xi;
+                      }
+                      if ($xi>$Apache::functionplotresponse::functionplotrulelabels{'end'}) {
+                         $Apache::functionplotresponse::functionplotrulelabels{'end'}=$xi;
+                      }
+                   }
 # Chain rule
 # dy/dx=dy/dt/(dx/dt)
                    my $dxdt=&ddt_cubic_hermite($t,@xparms);
@@ -738,9 +754,6 @@ sub start_functionplotresponse {
 
 sub compare_rel {
    my ($relationship,$value,$realval,$tol)=@_;
-   
-
-  &Apache::lonnet::logthis("Rel $relationship Val $value RV $realval T $tol");
 # is the real value defined?
    unless (defined($realval)) {
       if ($relationship eq 'eq') {
@@ -782,39 +795,42 @@ sub functionplotrulecheck {
    &Apache::lonnet::logthis("Rule $rule TolFunc $tolfunc TolDfDx $toldfdx TolD2fDx2 $told2fdx2");
    my ($label,$derivative,$xinitial,$xinitiallabel,$xfinal,$xfinallabel,$relationship,$value)
       =split(/\:/,$rule);
+
+   my $li=0;
+   my $lh=400;
+
 # if a hard value is set for the boundaries, it overrides the label
-   if (($xinitial ne '') && ($xinitiallabel ne '')) {
-      $Apache::functionplotresponse::functionplotrulelabels{$xinitiallabel}=$xinitial;
-   }
-   if (($xfinal ne '') && ($xfinallabel ne '')) {
-      $Apache::functionplotresponse::functionplotrulelabels{$xfinallabel}=$xfinal;
+   if (($xinitial ne '') && ($xinitiallabel ne '') && ($xinitiallabel ne 'start')) {
+      $li=&array_index($xmin,$xmax,$xinitial);
+      $Apache::functionplotresponse::functionplotrulelabels{$xinitiallabel}=$li;
+   }
+   if (($xfinal ne '') && ($xfinallabel ne '') && ($xfinallabel ne 'end')) {
+      $lh=&array_index($xmin,$xmax,$xfinal);
+      $Apache::functionplotresponse::functionplotrulelabels{$xfinallabel}=$lh;
    }
    if (defined($Apache::functionplotresponse::functionplotrulelabels{$xinitiallabel})) {
-      $xinitial=$Apache::functionplotresponse::functionplotrulelabels{$xinitiallabel};
+      $li=$Apache::functionplotresponse::functionplotrulelabels{$xinitiallabel};
+   } else {
+      $li=&array_index($xmin,$xmax,$xinitial);
    }
    if (defined($Apache::functionplotresponse::functionplotrulelabels{$xfinallabel})) {
-      $xfinal=$Apache::functionplotresponse::functionplotrulelabels{$xfinallabel};
+      $lh=$Apache::functionplotresponse::functionplotrulelabels{$xfinallabel};
+   } else {
+      $lh=&array_index($xmin,$xmax,$xfinal);
    }
 # Basic sanity checks
-   if ($xinitial eq '') {
-      $xinitial=0;
+   if ($li<0) { $li=0; }
+   if ($lh>400) { $lh=400; }
+   if ($li>$lh) {
+       $lh=$li;
    }
-   if ($xfinal eq '') {
-      $xfinal=$xinitial;
-   }
-   if ($xinitial>$xfinal) {
-       $xfinal=$xinitial;
-   }
-   &Apache::lonnet::logthis("Init $xinitial Final $xfinal");
+   &Apache::lonnet::logthis("Init $xinitial=$li Final $xfinal=$lh");
    my $tol=$tolfunc;
    if ($derivative==2) {
       $tol=$told2fdx2;
    } elsif ($derivative==1) {
       $tol=$toldfdx;
    }
-
-   my $li=&array_index($xmin,$xmax,$xinitial);
-   my $lh=&array_index($xmin,$xmax,$xfinal);
    for (my $i=$li; $i<=$lh; $i++) {
         my $val;
         if ($derivative==2) {
@@ -875,11 +891,13 @@ sub end_functionplotresponse {
         }
 
         my $ad='';
+        undef  %Apache::functionplotresponse::functionplotrulelabels;
+        $Apache::functionplotresponse::functionplotrulelabels{'start'}=400;
+        $Apache::functionplotresponse::functionplotrulelabels{'end'}=0;
         if (&populate_arrays($internalid,$xmin,$xmax) eq 'no_func') {
            $ad='NOT_FUNCTION';
         } else {
 # We have a function that we can actually grade, go through the spline rules.
-           undef  %Apache::functionplotresponse::functionplotrulelabels;
            foreach my $rule (@Apache::functionplotresponse::functionplotrules) {
               unless (&functionplotrulecheck($rule,$xmin,$xmax,$tolfunc,$toldfdx,$told2fdx2)) {
                  $ad='INCORRECT';