Re #9682. Handling case with one interpolation value.

mantidproject · Jun 27, 2014 · 167c634 · 167c634
1 parent 625079c
commit 167c634
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Showing 2 changed files with 16 additions and 2 deletions.
diff --git a/Code/Mantid/Framework/Kernel/src/Interpolation.cpp b/Code/Mantid/Framework/Kernel/src/Interpolation.cpp
@@ -60,9 +60,9 @@ namespace Kernel
   {
     size_t N = m_x.size();
 
-    if ( N == 0 )
+    if ( N < 2 )
     {
-      g_log.error() << "No data in Interpolation. Return interpolation value zero.";
+      g_log.error() << "Need at least two values for interpolation. Return interpolation value zero.";
       return 0.0;
     }
 

diff --git a/Code/Mantid/Framework/Kernel/test/InterpolationTest.h b/Code/Mantid/Framework/Kernel/test/InterpolationTest.h
@@ -59,6 +59,7 @@ class InterpolationTest : public CxxTest::TestSuite
         interpolation.setYUnit("dSpacing");
 
         interpolation.addPoint(200.0, 2.0);
+        interpolation.addPoint(202.0, 3.0);
 
         Interpolation other = interpolation;
 
@@ -193,6 +194,19 @@ class InterpolationTest : public CxxTest::TestSuite
         TS_ASSERT_THROWS(interpolation.findIndexOfNextLargerValue(m_tableXValues, 2000.0, 1, N - 1), std::range_error)
     }
 
+    void testInterpolationWithTooFewValues()
+    {
+        Interpolation interpolationZero;
+        Interpolation interpolationOne;
+        interpolationOne.addPoint(200, 2.0);
+
+        for(size_t i = 0; i < m_tableXValues.size(); ++i) {
+            // When there are only one or two values in the interpolation, it returns 0.0
+            checkValue(interpolationZero, m_tableXValues[i], 0.0, "zero interpolation values");
+            checkValue(interpolationOne, m_tableXValues[i], 0.0, "one interpolation value");
+        }
+    }
+
 private:
     Interpolation getInitializedInterpolation(std::string xUnit, std::string yUnit)
     {