fftn(API)
From EosPedia
DataManip/mrcImage/src/fftn is API for FFT.
constant
struct
API
Release memory
Release the used memory in fftn.c for FFT.
extern void fft_free (void);
FFT
double
extern int fftn (int ndim, const int dims[], double Re[], double Im[], int isign, double scaling);
float
extern int fftnf (int ndim, const int dims[], float Re[], float Im[], int isign, double scaling);
Re, Im: Input-Output
Variables mean
Variables in These API are used as the following.
Re[]: real value array Im[]: imaginary value array nTotal: total number of complex values nPass: number of elements involved in this pass of transform nSpan: nspan/nPass = number of bytes to increment pointer in Re[] and Im[] isign: exponent: +1 = forward -1 = reverse scaling: normalizing constant by which the final result is *divided* scaling == -1, normalize by total dimension of the transform scaling < -1, normalize by the square-root of the total dimension