Optimize genptable for coordinate solve (20x speedup)

1 files changed, 14 insertions, 0 deletions

diff --git a/src/utils/math.h b/src/utils/math.h
index 21fc60b..a9d9b85 100644
--- a/src/utils/math.h
+++ b/src/utils/math.h
@@ -10,6 +10,7 @@ STATIC void indextoperm(int64_t, size_t n, uint8_t [n]);
 STATIC int permsign(size_t n, const uint8_t [n]);
 STATIC int64_t digitstosumzero(size_t n, const uint8_t [n], uint8_t);
 STATIC void sumzerotodigits(int64_t, size_t n, uint8_t, uint8_t [n]);
+STATIC double intpow(double, uint64_t);
 
 STATIC int64_t
 factorial(int64_t n)
@@ -183,3 +184,16 @@ sumzerotodigits(int64_t d, size_t n, uint8_t b, uint8_t a[n])
 sumzerotodigits_error:
         memset(a, UINT8_ERROR, n);
 }
+
+STATIC double
+intpow(double b, uint64_t e)
+{
+        double r;
+
+        if (e == 0)
+                return 1;
+
+        r = intpow(b, e/2);
+
+        return e % 2 == 0 ? r * r : b * r * r;
+}