;making a histogram of randomly generated points
                                                                                                                                                             
;for random numnber you need a seed
iseed=-1234
;how many datapoints?
ndatapoints=100
;how many bins?
nbins=20
;make the data
data=randomn(iseed,ndatapoints)
;make a 'bin' vector of equally spaced centered bins between xmin and xmax
xmin = min(data)
xmax = max(data)
bins = xmin + findgen(nbins)/float(nbins-1)*(xmax-xmin)                                                                                                                                                             
; plot a histogram
plot,bins,histogram(data,min=xmin,max=xmax,nbins=nbins), $
psym=10,xrange=[-3.5,3.5]
                                                                                                                                                             
end