Fft

A class for calculating discrete fourier transform. The methods of this class use split format for complex data. This means that a complex data set is represented as two arrays - one for the real part and one for the imaginary part. An instance of this class can only be used for transforms of one particular size. The template parameter is the floating point type that the methods of the class will operate on.

struct Fft (

) {

void initialize(size_t n);

~this();

void fft(T[] re, T[] im);

void ifft(T[] re, T[] im);

static size_t alignment(size_t n);

static T[] allocate(size_t n);

static void deallocate(T[] arr);

static void scale(T[] data, T k);

}

Destructor

~this ~this(): Undocumented in source.

Members

Functions

fft void fft(T[] re, T[] im): Calculates discrete fourier transform. re should contain the real part of the data and im the imaginary part of the data. The method operates in place - the result is saved back to re and im. Both arrays must be properly aligned - to obtain a properly aligned array you can use allocate.
ifft void ifft(T[] re, T[] im): Calculates inverse discrete fourier transform scaled by n. The arguments have the same role as they do in fft.
initialize void initialize(size_t n): The Fft constructor. The parameter is the size of data sets that fft and ifft will operate on. I will refer to this number as n in the rest of the documentation for this class.Tables used in fft and ifft are calculated in the constructor.

Mixins

__anonymous mixin Import!T: Undocumented in source.

Static functions

alignment size_t alignment(size_t n): Returns requited alignment for use with fft, ifft and scale methods.
allocate T[] allocate(size_t n): Allocates an array that is aligned properly for use with fft, ifft and scale methods.
deallocate void deallocate(T[] arr): Deallocates an array allocated with allocate.
scale void scale(T[] data, T k): Scales an array data by factor k. The array must be properly aligned. To obtain a properly aligned array, use allocate.

Variables

log2n int log2n;: Undocumented in source.
table impl.Table table;: Undocumented in source.

Examples

import std.stdio, std.conv, std.exception;
import pfft.pfft;

void main(string[] args)
{
    auto n = to!int(args[1]);
    enforce((n & (n-1)) == 0, "N must be a power of two.");

    alias Fft!float F;

    F f;
    f.initialize(n);

    auto re = F.allocate(n);
    auto im = F.allocate(n);

    foreach(i, _; re)
        readf("%s %s\n", &re[i], &im[i]);

    f.fft(re, im);

    foreach(i, _; re)
        writefln("%s\t%s", re[i], im[i]);
}

Fft