Fix function that expands box limits.

It was ignoring the initial sign of the value and so sometimes the value would move in the wrong direction. Refs #11056
mantidproject · Mar 9, 2016 · 5209c40 · 5209c40
1 parent 192a80c
commit 5209c40
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Showing 2 changed files with 23 additions and 5 deletions.
diff --git a/Framework/Geometry/inc/MantidGeometry/MDGeometry/MDHistoDimensionBuilder.h b/Framework/Geometry/inc/MantidGeometry/MDGeometry/MDHistoDimensionBuilder.h
@@ -4,6 +4,8 @@
 #include "MantidGeometry/MDGeometry/MDHistoDimension.h"
 #include "MantidKernel/UnitLabel.h"
 
+#include <cmath>
+
 namespace Mantid {
 namespace Geometry {
 
@@ -33,11 +35,11 @@ class MANTID_GEOMETRY_DLL MDHistoDimensionBuilder {
     // Always use minimum float value as DBL_EPS is always too small
     static constexpr CoordT twoEps = 2 * std::numeric_limits<float>::epsilon();
     if (std::fabs(min) > twoEps)
-      min *= (1 + twoEps);
+      min *= (1 - std::copysign(twoEps, min));
     else
       min -= twoEps;
     if (std::fabs(max) > twoEps)
-      max *= (1 + twoEps);
+      max *= (1 + std::copysign(twoEps, max));
     else
       max += twoEps;
   }

diff --git a/Framework/Geometry/test/MDHistoDimensionBuilderTest.h b/Framework/Geometry/test/MDHistoDimensionBuilderTest.h
@@ -12,12 +12,28 @@ using Mantid::Geometry::IMDDimension_sptr;
 
 class MDHistoDimensionBuilderTest : public CxxTest::TestSuite {
 public:
-  void test_resizeToFit() {
+  void test_resizeToFit_Min_Positive_Max_Positive() {
+    const Mantid::coord_t min0(0.1f), max0(0.5f);
+    Mantid::coord_t min1(min0), max1(max0);
+    MDHistoDimensionBuilder::resizeToFitMDBox(min1, max1);
+    TS_ASSERT(min1 < min0);
+    TS_ASSERT(max1 > max0);
+  }
+
+  void test_resizeToFit_Min_Negative_Max_Positive() {
     const Mantid::coord_t min0(-0.1f), max0(0.5f);
     Mantid::coord_t min1(min0), max1(max0);
     MDHistoDimensionBuilder::resizeToFitMDBox(min1, max1);
-    TS_ASSERT_DIFFERS(min1, min0);
-    TS_ASSERT_DIFFERS(max1, max0);
+    TS_ASSERT(min1 < min0);
+    TS_ASSERT(max1 > max0);
+  }
+
+  void test_resizeToFit_Min_Negative_Max_Negative() {
+    const Mantid::coord_t min0(-0.5f), max0(-0.1f);
+    Mantid::coord_t min1(min0), max1(max0);
+    MDHistoDimensionBuilder::resizeToFitMDBox(min1, max1);
+    TS_ASSERT(min1 < min0);
+    TS_ASSERT(max1 > max0);
   }
 
   void testConstructRaw() {