On 5/21/07, Terrence Brannon <[EMAIL PROTECTED]> wrote:
On 5/20/07, John Randall <[EMAIL PROTECTED]> wrote:
> mp=:+/ .*
I do not understand the . * part of the expression +/ . *
Could you give some examples/ explanation of that? "Learning J" went
over it, but I can never find things in that bookafter I read it...
my bad I suppose.
See http://www.jsoftware.com/help/dictionary/d300.htm
essentially, . is defined such that x +/ .* y is the matrix product
of x and y.
More specifically, +/ .* is equivalent to +/@( *"1 _) and, in the general
case, that 1 is replaced with 1+lv where lv is the left rank of the right
argument to the . operation.
For example, < ., is equivalent to <@(,"_ _) because the rank of , is
infinite and 1+infinite is infinite.
--
Raul
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