polynomial: introduce a helper function to divide polynomial by ring element.

[ginac.git] / ginac / polynomial / ring_traits.hpp

diff --git a/ginac/polynomial/ring_traits.hpp b/ginac/polynomial/ring_traits.hpp
index 10fb172a5550be0626415879e8f0e423c0d4f7b4..540a6bd716e455eb7a084528b0d681ee3c8a08e9 100644 (file)
--- a/ginac/polynomial/ring_traits.hpp
+++ b/ginac/polynomial/ring_traits.hpp
@@ -10,6 +10,19 @@ static inline cln::cl_I div(const cln::cl_I& x, const cln::cl_I& y)
        return cln::exquo(x, y);
 }
 
+/// Exact integer division.
+/// Check if y divides x, if yes put the quotient into q, otherwise don't
+/// touch q. Returns true if y divides x and false if not.
+static inline bool div(cln::cl_I& q, const cln::cl_I& x, const cln::cl_I& y)
+{
+       const cln::cl_I_div_t qr = cln::truncate2(x, y);
+       if (zerop(qr.remainder)) {
+               q = qr.quotient;
+               return true;
+       }
+       return false;
+}
+
 static inline cln::cl_I get_ring_elt(const cln::cl_I& sample, const int val)
 {
        return cln::cl_I(val);