[S] question

Robert Lyles (rlyles@sph.jhu.edu)
Tue, 28 Apr 1998 15:02:37 -0400 (EDT)

I have a question on a particular computation in Splus:

Suppose "a" is a sequence of length n, and "b" is another sequence of
length m, where m<n. You would like to return a sequence of length n,
whose ith element (i=1,...,n) is the product over j=1,...,m of a function
like Phi(a_i + a_i*b_j). Here, Phi is the standard normal cdf ("pnorm"),
and i and j are being used to index the elements of "a" and "b",

My question for more experienced Splus users is, is there an efficient way
to do this, somehow taking advantage of the default matrix arithmetic
rules (i.e., if possible without using a "for" loop, etc.)?

Thanks very much for considering this question.

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