Roger Hui wrote: > It's the absolute value of y that should be bounded, > not just y itself. Thus: > > tcdf=: 4 : 0 > assert. (%:x)>|y > 0.5 + y * (!-:x-1) * ((0.5,-:1+x) H. 1.5 x%~-*:y) % (%:o.x) * !<:-:x > ) > > Mathworld <http://mathworld.wolfram.com/Studentst-Distribution.html> has different formulations (equations 7 and 8), which rely on the incomplete beta function and are not subject to the hypergeometric bounds.
I don't think the restriction is bad when x (degrees of freedom) is above about 10. For example 10 tcdf 3 0.993328 but it is not good if x is smaller. High values of y give strange results: 100 tcdf 9 _7.15204e15 Best wishes, John ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
