[gnumeric] Gamma: doc fix.

[Morten Welinder <mortenw src gnome org>]

commit 8786feca925ff9e81b084634a31fc44779ab395d
Author: Morten Welinder <terra gnome org>
Date:   Thu Jan 16 20:45:42 2014 -0500

    Gamma: doc fix.

 src/sf-gamma.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/src/sf-gamma.c b/src/sf-gamma.c
index ef204c5..a71c2f4 100644
--- a/src/sf-gamma.c
+++ b/src/sf-gamma.c
@@ -1154,6 +1154,10 @@ static const gnm_float lanczos_g = GNM_const (808618867.0) / 134217728;
  * Finally we recast that in terms of gamma's argument:
  *
  * N[CoefficientList[c13b /. z->(zp-1),{zp}],50]
+ *
+ * Enter complex numbers, exit simplicity.  The error bounds for the
+ * Lanczos approximation are bounds for the absolute value of the result.
+ * The relative error on one of the coordinates can be much higher.
  */
 static const gnm_float lanczos_num[] = {
        GNM_const(56906521.913471563880907910335591226868592353221448),