diff options
| author | Phil Burk <[email protected]> | 2015-11-02 18:59:55 -0800 |
|---|---|---|
| committer | Phil Burk <[email protected]> | 2015-11-02 18:59:55 -0800 |
| commit | d705eac3210391f32764166fdbb6ef9f96623134 (patch) | |
| tree | 611ce656a996d3e60ac32216280ad4b4c428f3e1 /src/com/softsynth/math | |
| parent | b19ff3c002edec62070cb6c6e8d5c2e321ff0354 (diff) | |
fix scaling in FFT
Diffstat (limited to 'src/com/softsynth/math')
| -rw-r--r-- | src/com/softsynth/math/FourierMath.java | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/src/com/softsynth/math/FourierMath.java b/src/com/softsynth/math/FourierMath.java index 82d4ec9..d133d7f 100644 --- a/src/com/softsynth/math/FourierMath.java +++ b/src/com/softsynth/math/FourierMath.java @@ -123,7 +123,7 @@ public class FourierMath { } public static void transform(int sign, int n, double ar[], double ai[]) { - double scale = Math.sqrt(1.0 / n); + double scale = (sign > 0) ? (2.0 / n) : (0.5); int numBits = FourierMath.numBits(n); int[] reverseTable = getReverseTable(numBits); @@ -150,7 +150,7 @@ public class FourierMath { int phase = 0; int phaseIncrement = numerator / (2 * mmax); for (int m = 0; m < mmax; ++m) { - double wr = sineTable[(phase + cosineOffset) & mask]; + double wr = sineTable[(phase + cosineOffset) & mask]; // cosine double wi = sineTable[phase]; for (i = m; i < n; i += stride) { @@ -170,7 +170,7 @@ public class FourierMath { } public static void transform(int sign, int n, float ar[], float ai[]) { - float scale = (float) Math.sqrt(1.0 / n); + float scale = (sign > 0) ? (2.0f / n) : (0.5f); int numBits = FourierMath.numBits(n); int[] reverseTable = getReverseTable(numBits); @@ -197,7 +197,7 @@ public class FourierMath { int phase = 0; int phaseIncrement = numerator / (2 * mmax); for (int m = 0; m < mmax; ++m) { - float wr = sineTable[(phase + cosineOffset) & mask]; + float wr = sineTable[(phase + cosineOffset) & mask]; // cosine float wi = sineTable[phase]; for (i = m; i < n; i += stride) { |