--- loncom/homework/functionplotresponse.pm	2010/11/07 01:57:50	1.25
+++ loncom/homework/functionplotresponse.pm	2010/11/07 11:15:37	1.26
@@ -1,7 +1,7 @@
 # LearningOnline Network with CAPA
 # option list style responses
 #
-# $Id: functionplotresponse.pm,v 1.25 2010/11/07 01:57:50 www Exp $
+# $Id: functionplotresponse.pm,v 1.26 2010/11/07 11:15:37 www Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -553,7 +553,7 @@ sub d2dt2_cubic_hermite {
 #
 sub array_index {
    my ($xmin,$xmax,$x)=@_;
-   return int(($x-$xmin)/($xmax-$xmin)*200.+0.5);
+   return int(($x-$xmin)/($xmax-$xmin)*400.+0.5);
 }
 
 #
@@ -562,32 +562,7 @@ sub array_index {
 
 sub index_x {
    my ($xmin,$xmax,$i)=@_;
-   return $i*($xmax-$xmin)/200.+$xmin;
-}
-
-#
-# Assume function to be linear between array points
-# Return the two indices and the scale factor
-#
-
-sub indices_scale {
-   my ($xmin,$xmax,$x)=@_;
-   my $i=&array_index($xmin,$xmax,$x);
-   my $xr=&index_x($xmin,$xmax,$i);
-   if ($xr<$x) {
-# Desired x is right of array index
-      if ($i>=200) { return (200,200,0); }
-      return($i,$i+1,200.*($x-$xr)/($xmax-$xmin));
-   } elsif ($xr>$x) {
-# Desired x is left of array index
-      if ($i<=0) { return (0,0,0); }
-      return($i-1,$i,1.-200.*($xr-$x)/($xmax-$xmin));
-   } else {
-# Desired x is at array index (unlikely, but ...)
-      if ($i>=200) { return (200,200,0); }
-      if ($i<=0) { return (0,0,0); }
-      return ($i,$i,0);
-   }
+   return $i*($xmax-$xmin)/400.+$xmin;
 }
 
 #
@@ -596,13 +571,7 @@ sub indices_scale {
 
 sub func_val {
    my ($xmin,$xmax,$x)=@_;
-   my ($il,$ih,$factor)=&indices_scale($xmin,$xmax,$x);
-   my $fl=$Apache::functionplotresponse::func[$il];
-   my $fh=$Apache::functionplotresponse::func[$ih];
-   unless (defined($fl) || defined($fh)) { return undef; }
-   unless (defined($fl)) { return $fh; }
-   unless (defined($fh)) { return $fl; }
-   return $fl+$factor*($fh-$fl);
+   return $Apache::functionplotresponse::func[&array_index($xmin,$xmax,$x)];
 }
 
 #
@@ -611,13 +580,7 @@ sub func_val {
 
 sub dfuncdx_val {
    my ($xmin,$xmax,$x)=@_;
-   my ($il,$ih,$factor)=&indices_scale($xmin,$xmax,$x);
-   my $fl=$Apache::functionplotresponse::dfuncdx[$il];
-   my $fh=$Apache::functionplotresponse::dfuncdx[$ih];
-   unless (defined($fl) || defined($fh)) { return undef; }
-   unless (defined($fl)) { return $fh; }
-   unless (defined($fh)) { return $fl; }
-   return $fl+$factor*($fh-$fl);
+   return $Apache::functionplotresponse::dfuncdx[&array_index($xmin,$xmax,$x)];
 }
 
 #
@@ -626,13 +589,7 @@ sub dfuncdx_val {
 
 sub d2funcdx2_val {
    my ($xmin,$xmax,$x)=@_;
-   my ($il,$ih,$factor)=&indices_scale($xmin,$xmax,$x);
-   my $fl=$Apache::functionplotresponse::d2funcdx2[$il];
-   my $fh=$Apache::functionplotresponse::d2funcdx2[$ih];
-   unless (defined($fl) || defined($fh)) { return undef; }
-   unless (defined($fl)) { return $fh; }
-   unless (defined($fh)) { return $fl; }
-   return $fl+$factor*($fh-$fl);
+   return $Apache::functionplotresponse::d2funcdx2[&array_index($xmin,$xmax,$x)];
 }
 
 #
@@ -641,7 +598,7 @@ sub d2funcdx2_val {
 
 sub populate_arrays {
     my ($id,$xmin,$xmax)=@_;
-    for (my $i=0; $i<=200; $i++) {
+    for (my $i=0; $i<=400; $i++) {
        $Apache::functionplotresponse::func[$i]=undef;
        $Apache::functionplotresponse::dfuncdx[$i]=undef;
        $Apache::functionplotresponse::d2funcd2x[$i]=undef;
@@ -662,10 +619,10 @@ sub populate_arrays {
                         $env{'form.HWVAL_'.$id.'_'.$label.'P'.$ni.'_y'},
                         $env{'form.HWVAL_'.$id.'_'.$label.'S'.$ni.'_y'});
 # Run in small steps over spline parameter
-            for (my $t=0; $t<=1; $t+=0.00025) {
+            for (my $t=0; $t<=1; $t+=0.0001) {
                 my $xi=&array_index($xmin,$xmax,&cubic_hermite($t,@xparms));
                 if ($xi<$xiold) { return 'no_func'; }
-                if (($xi>$xiold) && ($xi>=0) && ($xi<=200)) {
+                if (($xi>$xiold) && ($xi>=0) && ($xi<=400)) {
                    if (defined($Apache::functionplotresponse::func[$xi])) { return 'no_func'; }
                    $xiold=$xi;
 # Function value
@@ -786,8 +743,40 @@ sub start_functionplotresponse {
 }
 
 sub compare_rel {
-   my ($relationship,$value,$val,$tol)=@_;
-   if (abs($value-$val)<$tol) { return 1; }
+   my ($relationship,$value,$realval,$tol)=@_;
+# is the real value defined?
+   unless (defined($realval)) {
+      if ($relationship eq 'eq') {
+         if ($value eq 'undef') {
+            return 1;
+         } else {
+            return 0;
+         }
+      } elsif ($relationship eq 'ne') {
+         if ($value eq 'undef') {
+            return 0;
+         } else {
+            return 1;
+         }
+      } else {
+         return 0;
+      }
+   }
+
+# it is defined.
+   if ($relationship eq 'gt') {
+      return ($realval>$value);
+   } elsif ($relationship eq 'ge') {
+      return ($realval>$value-$tol);
+   } elsif ($relationship eq 'lt') {
+      return ($realval<$value);
+   } elsif ($relationship eq 'le') {
+      return ($realval<$value+$tol);
+   } elsif ($relationship eq 'ne') {
+      return (abs($value-$realval)>$tol);
+   } else {
+      return (abs($value-$realval)<$tol);
+   }
    return 0;
 }
 
@@ -876,7 +865,7 @@ sub end_functionplotresponse {
         $ymin=(defined($ymin)?$ymin:-10);
         my $ymax=&Apache::lonxml::get_param('ymax',$parstack,$safeeval);
         $ymax=(defined($ymax)?$ymax:10);
-        my $tolfunc=($ymax-$ymin)/100.;
+        my $tolfunc=5.*($ymax-$ymin)/100.;
         my $toldfdx=1;
         my $told2fdx2=1;
         if ($xmax>$xmin) {