CDF of the noncentral T Distribution

ASA243, a C library which computes the cumulative density function (CDF) of the noncentral Student's T probability density function, by Russell Lenth.

ASA243 is Applied Statistics Algorithm 243. Source code for many Applied Statistics Algorithms is available through STATLIB.


The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.


ASA243 is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version

Related Data and Programs:

ASA005, a C library which evaluates the CDF of the noncentral T distribution.

ASA076, a C library which evaluates the Owen's T function, needed to compute the CDF of the noncentral T distribution.


OWENS, a C library which evaluates Owen's T function.


Original FORTRAN77 version by Russell Lenth; C version by John Burkardt.


  1. William Guenther,
    Evaluation of probabilities for the noncentral distributions and difference of two T-variables with a desk calculator,
    Journal of Statistical Computation and Simulation,
    Volume 6, Number 3-4, 1978, pages 199-206.
  2. Russell Lenth,
    Algorithm AS 243: Cumulative Distribution Function of the Non-Central T Distribution,
    Applied Statistics,
    Volume 38, Number 1, 1989, pages 185-189.

Source Code:

Last revised on 31 May 2019.