[goffice] Math: add test for buggy math library.

[Morten Welinder <mortenw src gnome org>]

commit 292371bb556119118aea5c1a3ccf2ff159810a93
Author: Morten Welinder <terra gnome org>
Date:   Sun Mar 16 18:01:28 2014 -0400

    Math: add test for buggy math library.
    
    We rely on a mostly-working math library.  Warn users about trouble
    we know how to detect.

 ChangeLog              |    9 +++++++--
 goffice/math/go-math.c |    9 +++++++++
 2 files changed, 16 insertions(+), 2 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index bd666e1..0399434 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2014-03-16  Morten Welinder  <terra gnome org>
+
+       * goffice/math/go-math.c (_go_math_init): Add test for buggy math
+       library (probably caused by compiler bug).
+
 2014-03-15  Morten Welinder  <terra gnome org>
 
        * goffice/utils/go-pango-extras.c (go_pango_translate_here): Plug
@@ -10,8 +15,8 @@
 
 2014-03-15  Jean Brefort  <jean brefort normalesup org>
 
-       * goffice/canvas/goc-canvas.c (goc_canvas_init): really accept leave_notify
-       events. [#668103][see also #706659]
+       * goffice/canvas/goc-canvas.c (goc_canvas_init): really accept
+       leave_notify events. [#668103][see also #706659]
 
 2014-03-14 Andreas J. Guelzow <aguelzow pyrshep ca>
 
diff --git a/goffice/math/go-math.c b/goffice/math/go-math.c
index 5c534ca..574403a 100644
--- a/goffice/math/go-math.c
+++ b/goffice/math/go-math.c
@@ -176,6 +176,15 @@ _go_math_init (void)
        }
 #endif
 
+       {
+               double x = atof ("24985672148.49707");
+               double sx = sin (x);
+               double ref = -0.55266506738426566413304;
+               if (fabs (sx - ref) > 0.01) {
+                       g_warning ("Running with buggy math library, see 
https://bugzilla.gnome.org/show_bug.cgi?id=726250";);
+               }
+       }
+
        g_free (old_locale);
 #ifdef SIGFPE
        signal (SIGFPE, signal_handler);