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Generally, you should either use high-level Gwyddion functions such as gwy_data_field_fft_2d_raw()
or, if they are
insufficient, FFTW routines directly.
gint
gwy_fft_find_nice_size (gint size
);
Finds a nice-for-FFT array size.
Here ‘nice’ means three properties are guaranteed: it is greater than or equal to size
; it can be directly used
with current FFT backend without scaling (since 2.8 this is true for any size); and the transform is fast, i.e. the
number is highly factorable.
To be compatible with Gwyddion <= 2.7 one has to pass only data fields and lines with sizes returned by this function to raw integral transforms. Otherwise this function is mainly useful if you extend and pad the input data for other reasons and thus have the freedom to choose a convenient transform size.
void gwy_fft_window (gint n
,gdouble *data
,GwyWindowingType windowing
);
Multiplies data by given window.
void gwy_fft_window_data_field (GwyDataField *dfield
,GwyOrientation orientation
,GwyWindowingType windowing
);
Performs windowing of a data field in given direction.
This is an old alias for gwy_data_field_fft_window_1d()
.