[gnumeric] Docs.

[Morten Welinder <mortenw src gnome org>]

commit 604e504cb4ced8d9e33673e98d025aa0a7c2e97f
Author: Morten Welinder <terra gnome org>
Date:   Sat Jan 4 16:05:49 2014 -0500

    Docs.

 src/sf-gamma.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)
---
diff --git a/src/sf-gamma.c b/src/sf-gamma.c
index 8e6eb8d..ef204c5 100644
--- a/src/sf-gamma.c
+++ b/src/sf-gamma.c
@@ -592,7 +592,13 @@ gnm_lbeta3 (gnm_float a, gnm_float b, int *sign)
 }
 
 /* ------------------------------------------------------------------------- */
-
+/*
+ * This computes the E(x) such that
+ *
+ *   Gamma(x) = sqrt(2Pi) * x^(x-1/2) * exp(-x) * E(x)
+ *
+ * x should be >20 and the result is, roughly, 1+1/(12x).
+ */
 static void
 gamma_error_factor (GnmQuad *res, const GnmQuad *x)
 {