A brief description of exponentiation by squaring

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 6 insertions, 0 deletions

diff --git a/src/zpow.c b/src/zpow.c
index 7388bde..f709ff9 100644
--- a/src/zpow.c
+++ b/src/zpow.c
@@ -8,6 +8,12 @@
 void
 zpow(z_t a, z_t b, z_t c)
 {
+	/*
+	 * Exponentiation by squaring.
+	 * 
+	 * 7↑19 = 7↑10011₂ = 7↑2⁰ ⋅ 7↑2¹ ⋅ 7↑2⁴ where a↑2↑(n + 1) = (a↑2↑n)².
+	 */
+
 	size_t i, j, n, bits;
 	zahl_char_t x;