Ticket #3432: trac_3432_degrees.patch

a/sage/rings/polynomial/multi_polynomial_element.py

@@ -383 +383 @@
-        return gcd(self.coefficients(),integer=self.parent() is ZZ)
-
-    def degrees(self):
-
-list (precisely -- an \code{ETuple}) with the degree of 
-each variable in this polynomial.  The list of degrees is, of course, 
-
+r
+tuple (precisely -- an \code{ETuple}) with the
+degree of each variable in this polynomial.  The list of
+degrees is, of course, 
-
-        EXAMPLES:
-            sage: R.<x,y,z>=PolynomialRing(ZZ)

a/sage/rings/polynomial/multi_polynomial_libsingular.pyx

@@ -2181 +2181 @@
-        if(r != currRing): rChangeCurrRing(r)
-        return pLDeg(p,&l,r)
-
+    def degrees(self):
+        r""" 
+        Returns a tuple with the maximl degree of each variable in
+        this polynomial.  The list of degrees is ordered by the order
+        of the generators.
+
+        EXAMPLE:
+            sage: R.<y0,y1,y2> = PolynomialRing(QQ,3)
+            sage: q = 3*y0*y1*y1*y2; q 
+            3*y0*y1^2*y2 
+            sage: q.degrees() 
+            (1, 2, 1)
+            sage: (q + y0^5).degrees()
+            (5, 2, 1)
+        """
+        cdef poly *p = self._poly
+        cdef ring *r = (<MPolynomialRing_libsingular>self._parent)._ring
+        cdef int i
+        cdef list d = [0 for _ in range(r.N)]
+        while p:
+            for i from 0 <= i < r.N:
+                d[i] = max(d[i],p_GetExp(p, i+1, r))
+            p = pNext(p)
+        return tuple(d)
+
-    def coefficient(self, degrees):
-        """
-        Return the coefficient of the variables with the degrees