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Compute Tail Probabilities For An F-Statistic
 Syntax `ftail(`f`, `dfn`, `dfd`)` See Also ttail , cnormal

Description
Returns the element-by-element tail probability for an F-statistic, where f is a real or double-precision matrix with all its elements greater than 0, dfn is an integer matrix specifying the number of degrees of freedom in the numerator, and dfd is an integer matrix specifying the number of degrees of freedom in the denominator. ``` ```The tail probability for the F-statistic is ```       +infinity      /      | p(x, dfn, dfd) dx      /       f ```where `p(x, n, d)` is the probability density function for an F-distribution with `n` degrees of freedom in the numerator and `d` degrees of freedom in the denominator.

Example ```      f     = .1 : .1 : 10.      dfn   = 5      dfd   = 5      tail  = ftail(f, dfn, dfd)      gtitle("Tail of F-statistic")      gplot(f, tail) ``` returns the following plot: ``` ```