[Jprogramming] hypergeometric function in J

[elton wang]

Henry and Roger,
Thanks very much your kindly help. Just learned that there is relation between m H. n and (n-m) H. n. The erf function
erf   =: (1 H. 1.5)@*: * 2p_0.5&* % ^@:*:

may be rewritten to 
 erf2 =: ] * 2p_0.5 * [: 0.5 H.1.5 [: - *:, which is the one on http://en.wikipedia.org/wiki/Confluent_hypergeometric_function.