Changeset 3036:0594c5c5fb85

Timestamp:

02/09/07 12:16:37 (6 years ago)

Author:

'Martin Albrecht <malb@…

Branch:

default

Message:

added Ideal.integral_closure

Location:

sage

Files:

• interfaces/singular.py (modified) (1 diff)
• rings/multi_polynomial_ideal.py (modified) (1 diff)

sage/interfaces/singular.py

@@ -986 +986 @@
         if self.type() == 'matrix':
             return self.sage_matrix(R,sparse=False)
+        if self.type() == 'list':
+            return [ f._sage_(R) for f in self ]
+
+        NotImplementedError, "Coercion of this datatype not implemented yet"
 
     def set_ring(self):

sage/rings/multi_polynomial_ideal.py

@@ -477 +477 @@
         return S.ideal(r)
 
+    def integral_closure(self, p=0, r=True):
+        """
+        Let I == self.
+        
+        Returns the integral closure of I, ..., I^p, where sI
+        is an ideal in the polynomial ring R=k[x(1),...x(n)]. If p is
+        not given, or p==0, compute the closure of all powers up to
+        the maximum degree in t occurring in the closure of R[It] (so
+        this is the last power whose closure is not just the
+        sum/product of the smaller). If r is given and r is True,
+        I.integral_closure() starts with a check whether I is already a
+        radical ideal.
+
+        INPUT:
+            p -- powers of I (default: 0)
+            r -- check whether self is a radical ideal first (default: True)
+
+        EXAMPLE:
+            sage: R.<x,y> = QQ[]
+            sage: I = ideal([x^2,x*y^4,y^5])
+            sage: I.integral_closure()
+            [x^2, y^5, x*y^3]
+
+        ALGORITHM: Use Singular
+            
+        """
+        Is = self._singular_()
+        R = self.ring()
+        singular =Is .parent()
+        singular.load('reesclos.lib')
+        ret = Sequence([ R(f) for f in Is.normalI(p,int(r))[1] ], R,
+                       check=False, immutable=True)
+        return ret
+
     def reduce(self, f):
         """