public class FastFourierTransformer extends Object implements Serializable
There are several variants of the discrete Fourier transform, with various
normalization conventions, which are specified by the parameter
DftNormalization
.
The current implementation of the discrete Fourier transform as a fast Fourier transform requires the length of the data set to be a power of 2. This greatly simplifies and speeds up the code. Users can pad the data with zeros to meet this requirement. There are other flavors of FFT, for reference, see S. Winograd, On computing the discrete Fourier transform, Mathematics of Computation, 32 (1978), 175 - 199.
DftNormalization
,
Serialized FormConstructor and Description |
---|
FastFourierTransformer(DftNormalization normalization)
Creates a new instance of this class, with various normalization
conventions.
|
Modifier and Type | Method and Description |
---|---|
Object |
mdfft(Object mdca,
TransformType type)
Deprecated.
see MATH-736
|
Complex[] |
transform(Complex[] f,
TransformType type)
Returns the (forward, inverse) transform of the specified complex data set.
|
Complex[] |
transform(double[] f,
TransformType type)
Returns the (forward, inverse) transform of the specified real data set.
|
Complex[] |
transform(UnivariateFunction f,
double min,
double max,
int n,
TransformType type)
Returns the (forward, inverse) transform of the specified real function,
sampled on the specified interval.
|
static void |
transformInPlace(double[][] dataRI,
DftNormalization normalization,
TransformType type)
Computes the standard transform of the specified complex data.
|
public FastFourierTransformer(DftNormalization normalization)
normalization
- the type of normalization to be applied to the
transformed datapublic static void transformInPlace(double[][] dataRI, DftNormalization normalization, TransformType type)
dataRI[0][i]
is the real part of the i
-th data point,dataRI[1][i]
is the imaginary part of the i
-th data point.dataRI
- the two dimensional array of real and imaginary parts of the datanormalization
- the normalization to be applied to the transformed datatype
- the type of transform (forward, inverse) to be performedDimensionMismatchException
- if the number of rows of the specified
array is not two, or the array is not rectangularMathIllegalArgumentException
- if the number of data points is not
a power of twopublic Complex[] transform(double[] f, TransformType type)
f
- the real data array to be transformedtype
- the type of transform (forward, inverse) to be performedMathIllegalArgumentException
- if the length of the data array is not a power of twopublic Complex[] transform(UnivariateFunction f, double min, double max, int n, TransformType type)
f
- the function to be sampled and transformedmin
- the (inclusive) lower bound for the intervalmax
- the (exclusive) upper bound for the intervaln
- the number of sample pointstype
- the type of transform (forward, inverse) to be performedNumberIsTooLargeException
- if the lower bound is greater than, or equal to the upper boundNotStrictlyPositiveException
- if the number of sample points n
is negativeMathIllegalArgumentException
- if the number of sample points
n
is not a power of twopublic Complex[] transform(Complex[] f, TransformType type)
f
- the complex data array to be transformedtype
- the type of transform (forward, inverse) to be performedMathIllegalArgumentException
- if the length of the data array is not a power of two@Deprecated public Object mdfft(Object mdca, TransformType type)
transform(Complex[], TransformType)
in a row-column
implementation in any number of dimensions with
O(N×log(N)) complexity with
N = n1 × n2 ×n3 × ...
× nd, where nk is the number of elements in
dimension k, and d is the total number of dimensions.mdca
- Multi-Dimensional Complex Array, i.e. Complex[][][][]
type
- the type of transform (forward, inverse) to be performedmdca
as a Multi-Dimensional Complex Array, i.e. Complex[][][][]
IllegalArgumentException
- if any dimension is not a power of twoCopyright © 2003–2016 The Apache Software Foundation. All rights reserved.