scipy tutorial - Baustatik-Info-Server

SciPy Reference Guide, Release 0.8.dev
Examples
loc : array-like, optional
location parameter (default=0)
scale : array-like, optional
scale parameter (default=1)
size : int or tuple of ints, optional
shape of random variates (default computed from input arguments )
moments : string, optional
composed of letters [’mvsk’] specifying which moments to compute where ‘m’
= mean, ‘v’ = variance, ‘s’ = (Fisher’s) skew and ‘k’ = (Fisher’s) kurtosis. (default=’mv’)
>>> import matplotlib.pyplot as plt
>>> numargs = gamma.numargs
>>> [ a ] = [0.9,]*numargs
>>> rv = gamma(a)
Display frozen pdf
>>> x = np.linspace(0,np.minimum(rv.dist.b,3))
>>> h=plt.plot(x,rv.pdf(x))
Check accuracy of cdf and ppf
>>> prb = gamma.cdf(x,a)
>>> h=plt.semilogy(np.abs(x-gamma.ppf(prb,a))+1e-20)
Random number generation
>>> R = gamma.rvs(a,size=100)
Gamma distribution
For a = integer, this is the Erlang distribution, and for a=1 it is the exponential distribution.
gamma.pdf(x,a) = x**(a-1)*exp(-x)/gamma(a) for x >= 0, a > 0.
514 Chapter 3. Reference