From: nicolas <nicolas@git.imagemagick.org>
Date: Tue, 11 Dec 2012 15:27:48 +0000 (+0000)
Subject: (no commit message)
X-Git-Tag: 7.0.1-0~4623
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=564e05ecd66ac304817909c9ed31a6eca3a71714;p=imagemagick

---

diff --git a/MagickCore/resample.c b/MagickCore/resample.c
index e3477ddc3..a72b58bd4 100644
--- a/MagickCore/resample.c
+++ b/MagickCore/resample.c
@@ -894,6 +894,11 @@ static inline void ClampUpAxes(const double dux,const double dvx,
   const double frobenius_squared = n11+n22;
   const double discriminant =
     (frobenius_squared+twice_det)*(frobenius_squared-twice_det);
+  /*
+   * In exact arithmetic, discriminant can't be negative. In floating
+   * point, it can, because of the bad conditioning of SVD
+   * decompositions done through the associated normal matrix.
+   */
   const double sqrt_discriminant =
     sqrt(discriminant > 0.0 ? discriminant : 0.0);
   /*