hist normalise error?

I want to plot the probability density function, but

    > hist(...,normed=1,...) does not work as expected. Here is
    > the code (with ipython line prompts):

    > In [69]: n, bins, patches = hist(data, bins = 100, normed =
    > 1) [ 0.12485649, 0.03013777, 0.03874856, 0. , 0.00861079,
    > 0. , 0. , 0. , 0. , 0. , 0.0043054 , 0.0043054 , 0. ,
    > 0. , 0.0043054 , 0. , 0. , 0. , 0. , 0. , 0. ,
    > 0.0043054 , 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. ,
    > 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. ,
    > 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. ,
    > 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. ,
    > 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. ,
    > 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. ,
    > 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. ,
    > 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. ,
    > 0.0043054 ,] In [72]: sum(n) Out[72]: 0.22388059701492535

    > Should this not sum to 1.0 for it to be a PDF? Thanks

It should integrate to one

  import matplotlib.mlab
  matplotlib.mlab.trapz(bins, n)

JDH