TDIST

Calculates values for a Student's t-distribution.

Syntax:

TDIST(x, r, mode)

x is the value at which the distribution is calculated.

r, an integer >=1, is the degrees of freedom parameter for the t-distribution.

mode may be 1 or 2, to calculate the one or two tailed probability.

TDIST returns the probability density function for the t-distribution, calculating:

$\frac{mode\Gamma ((r+1)/2)}{\sqrt{\pi r}\Gamma (r/2)}(1+\frac{x^2}{r}{)}^{-\frac{r+1}{2}}$

Example:

TDIST(0.5, 2, 2)

returns approximately 0.666.