Change sparsity function for dense polys + add doctests

sagemath · Jul 4, 2014 · e89350e · e89350e
1 parent 7fec476
commit e89350e
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Showing 2 changed files with 65 additions and 10 deletions.
diff --git a/src/sage/rings/polynomial/polynomial_element.pyx b/src/sage/rings/polynomial/polynomial_element.pyx
@@ -4467,18 +4467,42 @@ cdef class Polynomial(CommutativeAlgebraElement):
         EXAMPLES::
 
             sage: R.<x> = ZZ[]
-            sage: f = x+x^4+x^7
-            sage: f.sparsity()
+            sage: (x+x^4+x^7).sparsity()
             3
+
+        TESTS::
+            sage: R.<x> = ZZ[]
+            sage: (x+x^4+x^7).sparsity()
+            3
+            sage: R(0).sparsity()
+            0
+            sage: R(1).sparsity()
+            1
+            sage: R.<x> = QQ[]
+            sage: (1/2*x+x^4+x^7/3).sparsity()
+            3
+            sage: R.<x> = QQbar[]
+            sage: (1-x+x^4+x^7).sparsity()
+            4
+            sage: R.<x> = GF(17)[]
+            sage: (1-x+17*x^4+x^7).sparsity()
+            3
+            sage: K.<a> = GF(3^5)
+            sage: R.<x> = K[]
+            sage: ((a^6-1)+x-a*x^4).sparsity()
+            3
+            sage: R.<x> = IntegerModRing(10)[]
+            sage: (1+x+10*x^2+12*x^3).sparsity()
+            3
+            sage: S = QuotientRing(R,Ideal(x^2-1))
+            sage: T.<t> = S[]
+            sage: ((9*x + 8)*t^4 + (5*x + 9)*t + x^2 + 4).sparsity()
+            3
+            sage: ((x^2+9)*t).sparsity()
+            0
         """
         zero = self.parent().base_ring().zero_element()
-        l = self.list()
-        cdef int c
-        while True:
-            try:
-                if l.pop() is not zero: c+=1
-            except IndexError:
-                return c
+        return len([c for c in self.list() if c != zero])
 
     def prec(self):
         """

diff --git a/src/sage/rings/polynomial/polynomial_element_generic.py b/src/sage/rings/polynomial/polynomial_element_generic.py
@@ -132,9 +132,40 @@ def sparsity(self):
         EXAMPLES::
 
             sage: R.<x> = PolynomialRing(ZZ,sparse=True)
-            sage: f = x+x^4+x^7
+            sage: f = x+x^43+x^72
             sage: f.sparsity()
             3
+            
+        TESTS::
+            sage: R.<x> = PolynomialRing(ZZ,sparse=True)
+            sage: (x+x^43+x^72).sparsity()
+            3
+            sage: R(0).sparsity()
+            0
+            sage: R(1).sparsity()
+            1
+            sage: R.<x> = PolynomialRing(QQ,sparse=True)
+            sage: (1/2*x+x^43+x^72/3).sparsity()
+            3
+            sage: R.<x> = PolynomialRing(QQbar,sparse=True)
+            sage: (1-x^27+x^43+x^72).sparsity()
+            4
+            sage: R.<x> = PolynomialRing(GF(17),sparse=True)
+            sage: (1-x^27+17*x^43+x^72).sparsity()
+            3
+            sage: K.<a> = GF(3^5)
+            sage: R.<x> = PolynomialRing(K,sparse=True)
+            sage: ((a^6-1)+x^27-a*x^43).sparsity()
+            3
+            sage: R.<x> = PolynomialRing(IntegerModRing(10),sparse=True)
+            sage: (1+x^17+10*x^2+12*x^3).sparsity()
+            3
+            sage: S = QuotientRing(R,Ideal(x^2-1))
+            sage: T.<t> = PolynomialRing(S,sparse=True)
+            sage: ((9*x + 8)*t^43 + (5*x + 9)*t^17 + x^2 + 4).sparsity()
+            3
+            sage: ((x^2+9)*t^78).sparsity()
+            0
         """
         return len(self.__coeffs)