--- loncom/homework/functionplotresponse.pm	2010/10/29 19:18:48	1.17
+++ loncom/homework/functionplotresponse.pm	2010/10/31 12:33:02	1.21
@@ -1,7 +1,7 @@
 # LearningOnline Network with CAPA
 # option list style responses
 #
-# $Id: functionplotresponse.pm,v 1.17 2010/10/29 19:18:48 www Exp $
+# $Id: functionplotresponse.pm,v 1.21 2010/10/31 12:33:02 www Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -499,6 +499,106 @@ sub d2dt2_cubic_hermite {
 }
 
 #
+# Array index calculation
+#
+sub array_index {
+   my ($xmin,$xmax,$x)=@_;
+   return int(($x-$xmin)/($xmax-$xmin)*200.+0.5);
+}
+
+#
+# Actual x-value of array index
+#
+
+sub index_x {
+   my ($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);
+   &Apache::lonnet::logthis("x:$x i:$i xr:$xr");
+   if ($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,$i,0);
+   }
+}
+
+#
+# Function value
+#
+
+sub func_val {
+   my ($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; }
+   my $func=$fl+$factor*($fh-$fl);
+   &Apache::lonnet::logthis("x:$x func:$func factor:$factor il:$il ih:$ih fil:$fl fih:$fh");
+   return $func;
+}
+
+#
+# Populate the arrays
+#
+
+sub populate_arrays {
+    my ($id,$xmin,$xmax)=@_;
+    for (my $i=0; $i<=200; $i++) {
+       $Apache::functionplotresponse::func[$i]=undef;
+       $Apache::functionplotresponse::dfunddx[$i]=undef;
+       $Apache::functionplotresponse::d2funcd2x[$i]=undef;
+    }
+    unless ($xmax>$xmin) { return 'no_func'; }
+# Run over all splines in response
+    foreach my $label (split(/\,/,$env{"form.HWVAL_AllSplines_$id"})) {
+        my $xiold=-1;
+# Run over all points in spline
+        for (my $i=1; $i<$env{"form.HWVAL_SplineOrder_".$id."_".$label}; $i++) {
+            my $ni=$i+1;
+            my @xparms=($env{'form.HWVAL_'.$id.'_'.$label.'P'.$i.'_x'},
+                        $env{'form.HWVAL_'.$id.'_'.$label.'S'.$i.'_x'},
+                        $env{'form.HWVAL_'.$id.'_'.$label.'P'.$ni.'_x'},
+                        $env{'form.HWVAL_'.$id.'_'.$label.'S'.$ni.'_x'});
+            my @yparms=($env{'form.HWVAL_'.$id.'_'.$label.'P'.$i.'_y'},
+                        $env{'form.HWVAL_'.$id.'_'.$label.'S'.$i.'_y'},
+                        $env{'form.HWVAL_'.$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) {
+                my $xi=&array_index($xmin,$xmax,&cubic_hermite($t,@xparms));
+                if ($xi<$xiold) { return 'no_func'; }
+                if (($xi>$xiold) && ($xi>=0) && ($xi<=200)) {
+                   if (defined($Apache::functionplotresponse::func[$xi])) { return 'no_func'; }
+                   $xiold=$xi;
+                   $Apache::functionplotresponse::func[$xi]=&cubic_hermite($t,@yparms);
+                }
+            }
+        }
+    }
+}
+
+#
 # Implentation of <functionplotresponse>
 #
 
@@ -525,13 +625,13 @@ sub start_functionplotresponse {
 
 # Parameters of <functionplotresponse>
   my $xmin=&Apache::lonxml::get_param('xmin',$parstack,$safeeval);
-  $xmin=($xmin?$xmin:-10);
+  $xmin=(defined($xmin)?$xmin:-10);
   my $xmax=&Apache::lonxml::get_param('xmax',$parstack,$safeeval);
-  $xmax=($xmax?$xmax:10);
+  $xmax=(defined($xmax)?$xmax:10);
   my $ymin=&Apache::lonxml::get_param('ymin',$parstack,$safeeval);
-  $ymin=($ymin?$ymin:-10);
+  $ymin=(defined($ymin)?$ymin:-10);
   my $ymax=&Apache::lonxml::get_param('ymax',$parstack,$safeeval);
-  $ymax=($ymax?$ymax:10);
+  $ymax=(defined($ymax)?$ymax:10);
   my $xaxisvisible=(&Apache::lonxml::get_param('xaxisvisible',$parstack,$safeeval)=~/on|true|yes|1/i?'true':'false');
   my $yaxisvisible=(&Apache::lonxml::get_param('yaxisvisible',$parstack,$safeeval)=~/on|true|yes|1/i?'true':'false');
   my $gridvisible=(&Apache::lonxml::get_param('gridvisible',$parstack,$safeeval)=~/on|true|yes|1/i?'true':'false');
@@ -612,7 +712,36 @@ sub end_functionplotresponse {
 #
 # Actually grade
 #
-        my $ad='INCORRECT';
+        my $xmin=&Apache::lonxml::get_param('xmin',$parstack,$safeeval);
+        $xmin=(defined($xmin)?$xmin:-10);
+        my $xmax=&Apache::lonxml::get_param('xmax',$parstack,$safeeval);
+        $xmax=(defined($xmax)?$xmax:10);
+        my $ad;
+        if (&populate_arrays($internalid,$xmin,$xmax) eq 'no_func') {
+           $ad='NOT_FUNCTION';
+        } else {
+           $ad='INCORRECT';
+        }
+        &func_val($xmin,$xmax,3.96);
+
+        &func_val($xmin,$xmax,3.965);
+
+        &func_val($xmin,$xmax,3.97);
+        &func_val($xmin,$xmax,3.975);
+        &func_val($xmin,$xmax,3.98);
+
+        &func_val($xmin,$xmax,3.985);
+        &func_val($xmin,$xmax,3.99);
+        &func_val($xmin,$xmax,3.995);
+
+        &func_val($xmin,$xmax,4);
+        &func_val($xmin,$xmax,4.05);
+        &func_val($xmin,$xmax,4.1);
+
+        &func_val($xmin,$xmax,4.15);
+        &func_val($xmin,$xmax,4.2);
+        &func_val($xmin,$xmax,4.25);
+
 #
 # Store grading info
 #