[WWcvs] pg: Fixed differentiation of log() function (it used to give an error about undefined function D_ln).

[dpvc v. a. <we...@ma...>]

Log Message:
-----------
Fixed differentiation of log() function (it used to give an error
about undefined function D_ln).

Modified Files:
--------------
    pg/lib/Parser:
        Differentiation.pm

Revision Data
-------------
Index: Differentiation.pm
===================================================================
RCS file: /webwork/cvs/system/pg/lib/Parser/Differentiation.pm,v
retrieving revision 1.14
retrieving revision 1.15
diff -Llib/Parser/Differentiation.pm -Llib/Parser/Differentiation.pm -u -r1.14 -r1.15
--- lib/Parser/Differentiation.pm
+++ lib/Parser/Differentiation.pm
@@ -536,9 +536,9 @@
 }
 
 sub Parser::Function::numeric::D_log {
-  my $self = $_[0];
+  my $self = shift;
   my $base10 = $self->{equation}{context}{flags}{useBaseTenLog};
-  if ($base10) {return D_log10(@_)} else {return D_ln(@_)}
+  if ($base10) {return $self->D_log10(@_)} else {return $self->D_ln(@_)}
 }
 
 sub Parser::Function::numeric::D_log10 {