Changeset bc76e8 in git for factory/canonicalform.cc

Timestamp:

Aug 29, 1997, 3:15:16 PM (27 years ago)

Author:

Jens Schmidt <schmidt@…>

Branches:

(u'spielwiese', 'fe61d9c35bf7c61f2b6cbf1b56e25e2f08d536cc')

Children:

45448d01d1185bac4b858ea8a686a5370e7d2161

Parents:

cfff6a26b7988bc4bfccd2c82b877fd314c3fce6

Message:

	* canonicalform.cc (deriv( Variable )): assertion added
	(deriv( Variable )): bug fix


git-svn-id: file:///usr/local/Singular/svn/trunk@644 2c84dea3-7e68-4137-9b89-c4e89433aadc

File:

• factory/canonicalform.cc (modified) (3 diffs)

factory/canonicalform.cc

@@ -1 +1 @@
 /* emacs edit mode for this file is -*- C++ -*- */
-/* $Id: canonicalform.cc,v 1.14 1997-08-04 14:57:41 schmidt Exp $ */
+/* $Id: canonicalform.cc,v 1.15 1997-08-29 13:15:16 schmidt Exp $ */
 
 #include <config.h>
@@ -358 +358 @@
 }
 
+//{{{ CanonicalForm CanonicalForm::deriv() const
+//{{{ docu
+//
+// deriv() - return the formal derivation of CO.
+//
+// Derives CO with respect to its main variable.  Returns zero if
+// f is in a coefficient domain.
+//
+//}}}
 CanonicalForm
 CanonicalForm::deriv() const
@@ -372 +381 @@
     }
 }
-
+//}}}
+
+//{{{ CanonicalForm CanonicalForm::deriv( const Variable & x ) const
+//{{{ docu
+//
+// deriv() - return the formal derivation of CO with respect to x.
+//
+// Note: If x is less than the main variable of CO we have to
+// swap variables which may be quite expensive.  x should be a
+// polynomial variable.  Returns zero if f is in a coefficient
+// domain.
+//
+//}}}
 CanonicalForm
 CanonicalForm::deriv( const Variable & x ) const
 {
-    if ( inCoeffDomain() )
+    ASSERT( x.level() > 0, "cannot derive with respect to algebraic variables" );
+    Variable y = mvar();
+    if ( inCoeffDomain() || x > y )
         return 0;
-    else {
-        CanonicalForm res = 0;
-        Variable y = mvar();
-        for ( CFIterator i = (y==x) ? *this : swapvar( *this, x, y ); i.hasTerms(); i++ )
-            if ( i.exp() > 0 )
-                res += power( y, i.exp()-1 ) * i.coeff() * i.exp();
-        return (y==x) ? res : swapvar( res, x, y );
-    }
-}
+    else if ( x == y )
+        return deriv();
+    else
+        return swapvar( swapvar( *this, x, y ).deriv( y ), x, y );
+}
+//}}}
 
 CanonicalForm