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Hypergeometric m H. n  0 0 0

The conjunction H. applies to two numeric lists to produce a monad which is the hypergeometric function defined in Section 15 of Abramowitz and Stegun [13]; it is the limit of the dyadic case, whose left argument restricts the number of terms of the approximating series.

As discussed in Iverson [14], the conjunction is defined as follows:
   rf=: 1 : '(,m) ^!.1/ i.@['          NB. Rising factorial
   L1=: 2 : 'm rf %&(*/) n rf'
   L2=: (i.@[ ^~ ]) % !@i.@[
   H =: 2 : '(m L1 n +/ . * L2) " 0'

For example:
   'a b'=: 2 3 5; 6 5

   a L1 b
(2 3 5 ^!.1/ i.@[) %&(*/) 6 5 ^!.1/ i.@[

   t=: 4 [ z=: 7

   t a L1 b z
1 1 1.71429 4.28571

   t (a H b , a H. b) z
295 295

   8 (1 H. 1) i. 6
1 2.71825 7.38095 19.8464 51.8063 128.619
   (1 H. 1) i. 6
1 2.71828 7.38906 20.0855 54.5982 148.413
   ^ i. 6
1 2.71828 7.38906 20.0855 54.5982 148.413

   erf   =: (1 H. 1.5)@*: * 2p_0.5&* % ^@:*:    NB. error function
   n01cdf=: -: @: >: @: erf @: ((%:0.5)&*)      NB. CDF of normal 0,1

   erf 0.5 1 1.5
0.5205 0.842701 0.966105
   n01cdf _2 _1.5 _1 _0.5 0 0.5 1 1.5 2
0.0227501 0.0668072 0.158655 0.308538 0.5 0.691462 0.841345 0.933193 0.97725


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