Esempio n. 1
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def pdtr(k, m):
    """Returns sum of left tail of Poisson distribution, 0 through k.

    See Cephes docs for details.
    """
    if k < 0:
        raise ValueError, "Poisson k must be >= 0."
    if m < 0:
        raise ValueError, "Poisson m must be >= 0."
    return igamc(k+1, m)
Esempio n. 2
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def chi_high(x, df):
    """Returns right-hand tail of chi-square distribution (x to infinity).
    
    df, the degrees of freedom, ranges from 1 to infinity (assume integers).
    Typically, df is (r-1)*(c-1) for a r by c table.
    
    Result ranges from 0 to 1.
    
    See Cephes docs for details.
    """
    x = fix_rounding_error(x)
    
    if x < 0:
        raise ValueError, "chi_high: x must be >= 0 (got %s)." % x
    if df < 1:
        raise ValueError, "chi_high: df must be >= 1 (got %s)." % df
    return igamc(df/2, x/2)
Esempio n. 3
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def gdtrc(a, b, x):
    """Returns integral from x to inf of Gamma distribution with params a and b.
    """
    if x < 0.0:
        return ZeroDivisionError, "x must be at least 0."
    return igamc(b, a * x)