From 5782a98041a40b3237c685bf8a47d6afbbd3593e Mon Sep 17 00:00:00 2001
From: Guillaume Chazarain <guichaz@gmail.com>
Date: Sat, 24 Apr 2010 19:57:00 +0200
Subject: [PATCH] Fix is_matrix_symmetry() to correctly choose between c1 and
 s1.

---
 src/matrix.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/matrix.c b/src/matrix.c
index d94b423..531e252 100644
--- a/src/matrix.c
+++ b/src/matrix.c
@@ -71,7 +71,7 @@ G_GNUC_PURE gfloat get_matrix_zoom(void)
 {
     /*
      * c1 == zoom*cos, s1 == zoom*sin
-     * cos^2 + sin^2 == 1 => c1^2 + s1^2 == zoom^2
+     * cos² + sin² == 1 => c1² + s1² == zoom²
      */
     return hypotf(MATRIX_C1, MATRIX_S1);
 }
@@ -222,10 +222,10 @@ G_GNUC_PURE gboolean is_matrix_symmetry(void)
      * c1 == c2  => rotation, c1 == -c2 => symmetry.
      * s1 == -s2 => rotation, s1 == s2 => symmetry.
      *
-     * Since c1^2 + s1^2 == 1, we use c1 only if far enough from 0.
+     * Since (c1/zoom)² + (s1/zoom)² == 1, we use c1 only if far enough from 0.
      */
 
-    return (MATRIX_C1 < -0.5 || MATRIX_C1 > 0.5) ?
+    return fabsf(MATRIX_C1) > fabsf(MATRIX_S1) ?
         !float_equal(MATRIX_C1, MATRIX_C2) :
         !float_equal(MATRIX_S1, -MATRIX_S2);
 }
-- 
2.11.4.GIT