Documentation.
Name:
alpha_exp_fft.pro
Purpose:
Calculate the power spectral index (alpha) by linear fit of the power spectral density (PSD) as a function of wavelength value, k. PSD is obtained by means of the 2D Fast Fourier Transform. Fourier wavelengths kx and ky
Calling sequence:
ALPHA_EXP_FFT, img, ind, bin, range, linfit_params
Input parameters:
img = Br, Blos, or Btot HARP cutout magnetogram corrected for limb presence.
ind = structure containing magnetogram's metada (resolution).
bin = Number of bins values in k-space for calculating the 1D PSD from the 2D PSD (angle integration). Optimal value for computation time/goo fit is 900
range = definition of the Inertial range for linear fit in units of Mm^-1 . Default values are 0.05 to 0. (or 2 - 20 Mm in linear size)
Optional input parameters:
None
Output parameters:
linfit_params - 3 elements 1D array containing the resulting parameters from the linear fit of PSD(k).
linfit_params[0] = slope of the linear fit (alpha exponent)
linfit_params[1] = 1-sigma error associated to the slope
linfit_params[2] = goodness-of-fit parameter value.
Property name in DB:
alpha_exp_fft_blos, alpha_exp_fft_br, alpha_exp_fft_btot
alpha_exp_fft_blos.alpha, alpha_exp_fft_blos.sigma, alpha_exp_fft_blos.fit_r
Repository:
https://dev.flarecast.eu/stash/projects/FE/repos/alpha_exp_fft-idl/browse