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java.lang.Objectmath.fourierTransforms.interleaved.RealFloatFFT
math.fourierTransforms.interleaved.RealFloatFFT_Radix2
public class RealFloatFFT_Radix2
Computes FFT's of real, single precision data where n is an integral power of 2. The physical layout of the mathematical data d[i] in the array data is as follows:
d[i] = data[i0 + stride*i]The FFT (D[i]) of real data (d[i]) is complex, but restricted by symmetry:
D[n-i] = conj(D[i])It turns out that there are still n `independent' values, so the transformation can still be carried out in-place. For RealFloatFFT_Radix2, the correspondence is as follows:
Logical | Physical | |
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Re(D[0]) | = | data[0] |
Im(D[0]) | = | 0 |
Re(D[1]) | = | data[1] |
Im(D[1]) | = | data[n-1] |
... | ... | |
Re(D[k]) | = | data[k] |
Im(D[k]) | = | data[n-k] |
... | ... | |
Re(D[n/2]) | = | data[n/2] |
Im(D[n/2]) | = | 0 |
... | ... | |
Re(D[n-k]) | = | data[k] |
Im(D[n-k]) | = | -data[n-k] |
... | ... | |
Re(D[n-1]) | = | data[1] |
Im(D[n-1]) | = | -data[n-1] |
Constructor Summary | |
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RealFloatFFT_Radix2(int n)
Create an FFT for transforming n points of real, single precision data. |
Method Summary | |
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void |
backtransform(float[] data,
int i0,
int stride)
Compute the (unnomalized) inverse FFT of data, leaving it in place. |
float[] |
toWraparoundOrder(float[] data)
Return data in wraparound order. |
float[] |
toWraparoundOrder(float[] data,
int i0,
int stride)
Return data in wraparound order. |
void |
transform(float[] data,
int i0,
int stride)
Compute the Fast Fourier Transform of data leaving the result in data. |
Methods inherited from class math.fourierTransforms.interleaved.RealFloatFFT |
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backtransform, inverse, inverse, normalization, transform |
Methods inherited from class java.lang.Object |
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equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public RealFloatFFT_Radix2(int n)
Method Detail |
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public void transform(float[] data, int i0, int stride)
transform
in class RealFloatFFT
public void backtransform(float[] data, int i0, int stride)
transform
.
backtransform
in class RealFloatFFT
public float[] toWraparoundOrder(float[] data)
toWraparoundOrder
in class RealFloatFFT
public float[] toWraparoundOrder(float[] data, int i0, int stride)
toWraparoundOrder
in class RealFloatFFT
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