Simpler version of `PSF_GAUSSIAN` in IDL.

gausspsf2d.py

""" 
Simpler version of `PSF_GAUSSIAN` in IDL. 
:Authors: Pey Lian Lim (Python) 
:Organization: Space Telescope Science Institute 
:History: 
    * 2010/08/17 PLL converted from IDL to Python. 
"""

# External modules 
import numpy 
#----------- 

def GaussPsf2D(npix, fwhm, normalize=True): 
    """ 
    Parameters 
    ---------- 
    npix: int 
        Number of pixels for each dimension. 
        Just one number to make all sizes equal. 
    fwhm: float 
        FWHM (pixels) in each dimension. 
        Single number to make all the same. 
    normalize: bool, optional 
        Normalized so total PSF is 1. 
    Returns 
    ------- 
    psf: array_like 
        Gaussian point spread function. 
    """ 
    # Initialize PSF params 
    cntrd = (npix - 1.0) * 0.5 
    st_dev = 0.5 * fwhm / numpy.sqrt( 2.0 * numpy.log(2) ) 
    # Make PSF 
    i = range(npix) 
    psf = numpy.array( [numpy.exp(-(((cntrd-x)/st_dev)**2+((cntrd-y)/st_dev)**2)/2) for x in i for y in i] ) 
    psf = psf.reshape(npix, npix) 
    # Normalize 
    if normalize: psf /= psf.sum() 
    return psf