Function Description

KML_FFT is a math library of fast Fourier transform (FFT). It is the fast computing methods of discrete Fourier transform (DFT) and inverse discrete Fourier transform (IDFT), and is widely used in the fields of engineering, science, and mathematics. KML_FFT reduces the complexity of Fourier transform calculation from O(n²) to O(n log n), and is listed in the top 10 algorithms of the 20th century by the IEEE Computing in Science & Engineering.

The Fast Fourier Transform (FFT) library contains a series of interface standards for FFT functions. The KML_FFT library contains the following four types of functions:

• Plan functions: used to create a plan for an FFT. After a plan is used, call the kml_fft(f)_destroy_plan function to release it.
  • C2C Transforms: FFT from a complex number to another complex number
  • R2C Transforms: FFT from a real number to a complex number
  • C2R Transforms: FFT from a complex number to a real number
  • R2R Transforms: FFT from a real number to another real number
• Transform execution functions: used to execute an FFT based on the plan.
• Memory functions: used to allocate and release a memory space.
• Thread functions: used to initialize a thread and release related resources.

For the previous transforms, the KML_FFT library supports:

• In-place transform (the input and output have the same pointer) and out-place transform.
• Single precision and double precision: Single-precision functions use kml_fftf_ as the function prefix, and double-precision functions use kml_fft_ as the function prefix. Function Syntax provides examples of double-precision functions.