Interpolator: Cosine option is now overloaded and passing tests. issue …

…#71
jamoma · Dec 30, 2015 · ef1f1f3 · ef1f1f3
1 parent 2d6fa09
commit ef1f1f3
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Showing 2 changed files with 32 additions and 6 deletions.
diff --git a/include/core/JamomaInterpolator.h b/include/core/JamomaInterpolator.h
@@ -111,8 +111,10 @@ namespace Jamoma {
 
 
 		/** Cosine interpolation
-			@param x0		Sample value at prior integer index
-			@param x1		Sample value at next integer index
+            @param x0		Unused sample value
+            @param x1		Sample value at prior integer index
+			@param x2		Sample value at next integer index
+            @param x3		Unused sample value
 			@param delta 	Fractional location between x0 (delta=0) and x1 (delta=1)
 			@return			The interpolated value
 		 */
@@ -121,10 +123,16 @@ namespace Jamoma {
 		public:
 			static const int 	delay = 1;
 
-			constexpr T operator()(T x0, T x1, double delta) noexcept {
+			constexpr T operator()(T x1, T x2, double delta) noexcept {
 				T a = 0.5 * (1.0 - cos(delta * kPi));
-				return x0 + a * (x1-x0);
+				return x1 + a * (x2-x1);
 			}
+
+            constexpr T operator()(T x0, T x1, T x2, T x3, double delta) noexcept {
+                // NW: ideally we would call the operator above to remain DRY, but I could not get syntax right
+                T a = 0.5 * (1.0 - cos(delta * kPi));
+                return x1 + a * (x2-x1);
+            }
 		};
 
 

diff --git a/test/Interpolator/Interpolator.cpp b/test/Interpolator/Interpolator.cpp
@@ -216,10 +216,10 @@ class InterpolatorTest {
         int		badSampleCount = 0;
         Jamoma::Interpolator::Cosine<Jamoma::Sample> my_interp;
 
-        //auto 	x0 = -1.0;
+        auto 	x0 = -1.0;
         auto	x1 =  2.0;
         auto    x2 =  1.0;
-        //auto    x3 =  4.0;
+        auto    x3 =  4.0;
 
         // The following output was generated using the Octave code
         // in InterpolatorTargetOutput.m by NW
@@ -305,6 +305,24 @@ class InterpolatorTest {
         }
 
 		mTest->TEST_ASSERT("testCosine produced correct interpolation output", badSampleCount == 0);
+
+        // reset varaiables
+        badSampleCount = 0;
+        temp = 0.0;
+        tempExpected = 0.0;
+        delta = 0.0;
+
+        for (int i = 0; i < expectedOutputCosine.size(); i++) {
+            delta = (i + 1.0) / 64.0;
+            temp = my_interp(x0,x1,x2,x3,delta);
+            tempExpected = expectedOutputCosine[i];
+            if (! mTest->compare(temp, tempExpected, true, 8) ) {
+                badSampleCount++;
+                std::cout << "sample " << i << " had a difference of " << std::fabs(temp - tempExpected) << std::endl;
+            }
+        }
+
+        mTest->TEST_ASSERT("testCosine overloaded operator produced consistent output", badSampleCount == 0);
 	}