t Distribution Function
(Student's) t-distribution with f degrees of freedom
is defined to be the distribution of T = Y/(Z/f)1/2,
where Y has the normal(0,1) distribution, Z has the
chi-square distribution with f degrees of freedom,
and Y and Z are independent.
The t-distribution with 1 degree of freedom is the Cauchy distribution.
For example, t(1,1)=.75