j - Arithmetic mean forwards vs backwards? -
i'm familiar way of doing arithmetic mean in j:
+/ % #
but it's shown here as
# %~ +/
are these 2 versions interchangeable, , if not when should use 1 versus other?
dyadic ~
reverses arguments of verb. x f~ y
equivalent y f x
. use ~
when you, um, want reverse arguments of verb.
one of common uses forks , hooks composition. example, because y f (g y)
(f g) y
can use ((f~) g) y
when need (g y) f y
.
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