Module « scipy.special »

Fonction fdtr - module scipy.special

Signature de la fonction fdtr

Description

fdtr.__doc__

fdtr(x1, x2, x3, /, out=None, *, where=True, casting='same_kind', order='K', dtype=None, subok=True[, signature, extobj])

fdtr(dfn, dfd, x)

F cumulative distribution function.

Returns the value of the cumulative distribution function of the
F-distribution, also known as Snedecor's F-distribution or the
Fisher-Snedecor distribution.

The F-distribution with parameters :math:`d_n` and :math:`d_d` is the
distribution of the random variable,

.. math::
    X = \frac{U_n/d_n}{U_d/d_d},

where :math:`U_n` and :math:`U_d` are random variables distributed
:math:`\chi^2`, with :math:`d_n` and :math:`d_d` degrees of freedom,
respectively.

Parameters
----------
dfn : array_like
    First parameter (positive float).
dfd : array_like
    Second parameter (positive float).
x : array_like
    Argument (nonnegative float).

Returns
-------
y : ndarray
    The CDF of the F-distribution with parameters `dfn` and `dfd` at `x`.

Notes
-----
The regularized incomplete beta function is used, according to the
formula,

.. math::
    F(d_n, d_d; x) = I_{xd_n/(d_d + xd_n)}(d_n/2, d_d/2).

Wrapper for the Cephes [1]_ routine `fdtr`.

References
----------
.. [1] Cephes Mathematical Functions Library,
       http://www.netlib.org/cephes/