[SciPy-user] Strange discontinuity in noncentral chisquare

Neal Becker ndbecker2@gmail....
Thu May 28 12:56:56 CDT 2009


def pmiss2 (x, esnodB, N):
    esno = 10**(0.1 * esnodB) * N
    var = 1/esno
    _lambda = 1/(0.5*var)

    return ncx2.cdf (x, 2, _lambda)

x = np.arange (0, 50, 0.1)
p1 = [pmiss2 (e, 3.5, 24) for e in x]

What's with this strange discontinuity?
print p1:
...
3.475382846574262e-21,
 4.2226227741362447e-21,
 5.1248671653198949e-21,
 6.2130949241675783e-21,
 7.5242411687161146e-21,
 9.1022970542215721e-21,
 5.8787514615651664e-09,
 6.2565279721932619e-09,
 6.656924144742753e-09,
 7.0811937641411923e-09,
 7.5306544171300622e-09,
 8.0066904400027596e-09,
 8.5107559880675483e-09,
 9.044378231221098e-09,
 9.6091606801490766e-09,
...




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