Module « scipy.special »

Fonction chdtrc - module scipy.special

Signature de la fonction chdtrc

Description

chdtrc.__doc__

chdtrc(x1, x2, /, out=None, *, where=True, casting='same_kind', order='K', dtype=None, subok=True[, signature, extobj])

chdtrc(v, x, out=None)

Chi square survival function.

Returns the area under the right hand tail (from `x` to infinity)
of the Chi square probability density function with `v` degrees of
freedom:

.. math::

    \frac{1}{2^{v/2} \Gamma(v/2)} \int_x^\infty t^{v/2 - 1} e^{-t/2} dt

Here :math:`\Gamma` is the Gamma function; see `gamma`. This
integral can be expressed in terms of the regularized upper
incomplete gamma function `gammaincc` as
``gammaincc(v / 2, x / 2)``. [1]_

Parameters
----------
v : array_like
    Degrees of freedom.
x : array_like
    Lower bound of the integral.
out : ndarray, optional
    Optional output array for the function results.

Returns
-------
scalar or ndarray
    Values of the survival function.

See Also
--------
chdtr, chdtri, chdtriv, gammaincc

References
----------
.. [1] Chi-Square distribution,
    https://www.itl.nist.gov/div898/handbook/eda/section3/eda3666.htm

Examples
--------
>>> import scipy.special as sc

It can be expressed in terms of the regularized upper incomplete
gamma function.

>>> v = 1
>>> x = np.arange(4)
>>> sc.chdtrc(v, x)
array([1.        , 0.31731051, 0.15729921, 0.08326452])
>>> sc.gammaincc(v / 2, x / 2)
array([1.        , 0.31731051, 0.15729921, 0.08326452])