Hello Terrence;
The choice of indices does not seem to follow a pattern I recognize.
What is the context for this definition?
bill lam wrote:
I think that this is a little bit more readable,
compose =: 4 : 0
a =. ((0{x) * (0{y))
b =. ((0{x) * (1{y)) + ((1{x) * (3{y))
c =. ((2{x) * (0{y)) + ((3{x) * (2{y))
d =. ((2{x) * (1{y)) + ((3{x) * (3{y))
a,b,c,d
)
Hope that this sort of expressions will not happen frequently.
Terrence Brannon wrote:
To be an array processing language, I am surprised to find the Pike
code more
readable for this particular problem. Please spruce up my J code.
compose =: 4 : 0
a =. ((0 { x) * (0 { y))
b =. ((0 { x) * (1 { y)) + ((1 { x) * (3 { y)) c =. ((2 { x) * (0 {
y)) + ((3 { x) * (2 { y)) d =. ((2 { x) * (1 { y)) + ((3 { x) * (3 { y))
a,b,c,d
)
-- Pike code follows --
array(int) compose(array(int) a, array(int) b)
{
return ({ a[0]*b[0], a[0]*b[1]+a[1]*b[3],
a[2]*b[0]+a[3]*b[2], a[2]*b[1]+a[3]*b[3] });
}
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later ...
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