scipy.special.ncfdtridfn¶

scipy.special.
ncfdtridfn
(p, dfd, nc, f) = <ufunc 'ncfdtridfn'>¶ Calculate degrees of freedom (numerator) for the noncentral Fdistribution.
This is the inverse with respect to dfn of
ncfdtr
. Seencfdtr
for more details.Parameters: p : array_like
Value of the cumulative distribution function. Must be in the range [0, 1].
dfd : array_like
Degrees of freedom of the denominator sum of squares. Range (0, inf).
nc : array_like
Noncentrality parameter. Should be in range (0, 1e4).
f : float
Quantiles, i.e. the upper limit of integration.
Returns: dfn : float
Degrees of freedom of the numerator sum of squares.
See also
Notes
The value of the cumulative noncentral F distribution is not necessarily monotone in either degrees of freedom. There thus may be two values that provide a given CDF value. This routine assumes monotonicity and will find an arbitrary one of the two values.
Examples
>>> from scipy.special import ncfdtr, ncfdtridfn
Compute the CDF for several values of dfn:
>>> dfn = [1, 2, 3] >>> p = ncfdtr(dfn, 2, 0.25, 15) >>> p array([ 0.92562363, 0.93020416, 0.93188394])
Compute the inverse. We recover the values of dfn, as expected:
>>> ncfdtridfn(p, 2, 0.25, 15) array([ 1., 2., 3.])