; computes the probability density function of input_data
; written by C. Federrath, 2017
pro get_pdf_astr4004, input_data, MIN=min, MAX=max, NBINS=nbins, $
    HIST=hist, PDF=pdf, CDF=cdf, LOC=loc, BINSIZE=binsize

    if not keyword_set(min) then min = min(input_data)
    if not keyword_set(max) then max = max(input_data)
    if not keyword_set(nbins) then nbins = 100

    binsize = (max-min) / double(nbins)
    hist = histogram(input_data, binsize=binsize, min=min, max=max, locations=loc)
    pdf = hist / total(hist, /double) / binsize
    cdf = total(pdf, /cumulative) * binsize

end ; ==============================