Some improvements to GeometryFeatures and TemporalFeatures. A new tes…

…t for confirming that a reverse FFT applied to the FFT output reproduces the original signal.
almostrealism · Oct 5, 2024 · 4374514 · 4374514
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commit 4374514
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Showing 3 changed files with 71 additions and 8 deletions.
diff --git a/geometry/src/main/java/org/almostrealism/geometry/GeometryFeatures.java b/geometry/src/main/java/org/almostrealism/geometry/GeometryFeatures.java
@@ -65,6 +65,20 @@ default <T extends PackedCollection<?>> CollectionProducer<T> tanh(Supplier<Eval
 				null, (Producer) input);
 	}
 
+
+	default CollectionProducer<PackedCollection<?>> sinw(Producer<PackedCollection<?>> input,
+														 Producer<PackedCollection<?>> wavelength,
+														 Producer<PackedCollection<?>> amp) {
+		return sin(c(TWO_PI).multiply(input).divide(wavelength)).multiply(amp);
+	}
+
+	default CollectionProducer<PackedCollection<?>> sinw(Producer<PackedCollection<?>> input,
+														 Producer<PackedCollection<?>> wavelength,
+														 Producer<PackedCollection<?>> phase,
+														 Producer<PackedCollection<?>> amp) {
+		return sin(c(TWO_PI).multiply(divide(input, wavelength).subtract(phase))).multiply(amp);
+	}
+
 	@Deprecated
 	default ExpressionComputation relativeSin(Supplier<Evaluable<? extends PackedCollection<?>>> input) {
 		Function<List<ArrayVariable<Double>>, Expression<Double>> exp = args ->
@@ -79,16 +93,16 @@ default ExpressionComputation relativeCos(Supplier<Evaluable<? extends PackedCol
 		return new ExpressionComputation(List.of(exp), input);
 	}
 
-	default CollectionProducer<PackedCollection<?>> sinw(Producer<PackedCollection<?>> input,
-														 Producer<PackedCollection<?>> wavelength,
-														 Producer<PackedCollection<?>> amp) {
+	default CollectionProducer<PackedCollection<?>> relativeSinw(Producer<PackedCollection<?>> input,
+																 Producer<PackedCollection<?>> wavelength,
+																 Producer<PackedCollection<?>> amp) {
 		return relativeSin(c(TWO_PI).multiply(input).divide(wavelength)).multiply(amp);
 	}
 
-	default CollectionProducer<PackedCollection<?>> sinw(Producer<PackedCollection<?>> input,
-																							 Producer<PackedCollection<?>> wavelength,
-																							 Producer<PackedCollection<?>> phase,
-																							 Producer<PackedCollection<?>> amp) {
+	default CollectionProducer<PackedCollection<?>> relativeSinw(Producer<PackedCollection<?>> input,
+																 Producer<PackedCollection<?>> wavelength,
+																 Producer<PackedCollection<?>> phase,
+																 Producer<PackedCollection<?>> amp) {
 		return relativeSin(c(TWO_PI).multiply(divide(input, wavelength).subtract(phase))).multiply(amp);
 	}
 

diff --git a/time/src/main/java/org/almostrealism/time/TemporalFeatures.java b/time/src/main/java/org/almostrealism/time/TemporalFeatures.java
@@ -96,7 +96,12 @@ default Interpolate interpolate(
 	}
 
 	default FourierTransform fft(int bins, Producer<PackedCollection<?>> input, ComputeRequirement... requirements) {
-		FourierTransform fft = new FourierTransform(bins, input);
+		return fft(bins, false, input, requirements);
+	}
+
+	default FourierTransform fft(int bins, boolean inverse,
+								 Producer<PackedCollection<?>> input, ComputeRequirement... requirements) {
+		FourierTransform fft = new FourierTransform(bins, inverse, input);
 		if (requirements.length > 0) fft.setComputeRequirements(List.of(requirements));
 		return fft;
 	}

diff --git a/utils/src/test/java/org/almostrealism/time/computations/test/FourierTransformTests.java b/utils/src/test/java/org/almostrealism/time/computations/test/FourierTransformTests.java
@@ -18,8 +18,10 @@
 
 import io.almostrealism.code.ComputeRequirement;
 import org.almostrealism.collect.PackedCollection;
+import org.almostrealism.time.Frequency;
 import org.almostrealism.time.computations.FourierTransform;
 import org.almostrealism.util.TestFeatures;
+import org.junit.Assert;
 import org.junit.Test;
 
 import java.util.List;
@@ -48,4 +50,46 @@ public void compile(ComputeRequirement requirement) {
 		ft.setComputeRequirements(List.of(requirement));
 		ft.get().evaluate();
 	}
+
+	@Test
+	public void forwardAndInverse() {
+		forwardAndInverse(ComputeRequirement.CPU);
+	}
+
+	public void forwardAndInverse(ComputeRequirement requirement) {
+		int bins = 1024;
+		Frequency f1 = new Frequency(440.00);
+		Frequency f2 = new Frequency(587.33);
+
+		PackedCollection<?> input = new PackedCollection<>(2, bins);
+
+		a(cp(input.range(shape(bins)).each()),
+				add(
+						sinw(integers(0, bins), c(f1.getWaveLength()), c(0.9)),
+						sinw(integers(0, bins), c(f2.getWaveLength()), c(0.6))))
+				.get().run();
+
+		FourierTransform ft = fft(bins, cp(input), requirement);
+		PackedCollection<?> out = ft.get().evaluate();
+		log(out.getShape());
+
+		FourierTransform ift = fft(bins, true, cp(out), requirement);
+		PackedCollection<?> reversed = ift.get().evaluate();
+		log(reversed.getShape());
+
+		int total = 0;
+
+		for (int i = 0; i < bins; i++) {
+			double expected = bins * input.valueAt(0, i);
+
+			if (expected != 0) {
+				double actual = reversed.toDouble(i);
+				log(expected + " vs " + actual);
+				assertSimilar(expected, actual, 0.0001);
+				total++;
+			}
+		}
+
+		Assert.assertTrue(total > (bins * 0.9));
+	}
 }