aboutsummaryrefslogtreecommitdiff
path: root/zmodn.h
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--zmodn.h8
1 files changed, 5 insertions, 3 deletions
diff --git a/zmodn.h b/zmodn.h
index fdb1ee6..890fb0e 100644
--- a/zmodn.h
+++ b/zmodn.h
@@ -40,13 +40,15 @@ public:
40 bool operator!=(const Zmod& z) const { return value != z.value; } 40 bool operator!=(const Zmod& z) const { return value != z.value; }
41 41
42 std::optional<Zmod> inverse() const { 42 std::optional<Zmod> inverse() const {
43 auto [g, a, _] = extended_gcd(value, N); 43 auto [g, a, b] = extended_gcd(value, N);
44 return g == 1 ? Zmod(a) : std::optional<Zmod>{}; 44 return g == 1 ? Zmod(a) : std::optional<Zmod>{};
45 } 45 }
46 46
47 std::optional<Zmod> operator/(const Zmod& d) const { 47 std::optional<Zmod> operator/(const Zmod& d) const {
48 auto i = d.inverse(); 48 auto [g, x, y] = extended_gcd(value, d.toint());
49 return i ? (*this) * i.value() : i; 49 auto [a, b] = std::pair<Zmod, Zmod>{value / g, d.toint() / g};
50 auto i = b.inverse();
51 return i ? a * i.value() : i;
50 } 52 }
51 53
52 std::optional<Zmod> operator/=(const Zmod& d) { 54 std::optional<Zmod> operator/=(const Zmod& d) {