Jacobs, Jan wrote:
> John,
> In my function f I have to access a global array (Gh and T) and I do
need the iteration count for that. The context is stochastic image
processing and I use a Simulated Annealing scheme.
> My f looks like:
> f=:3 : 0
> 'state index'=.y.
> nstate=.index{Gh
> TEMP=.index{T
> e=. (lhood state) + state prior state
> ne=. (lhood nstate) + nstate prior state
> de=. ne - e
> accept=. de <: - TEMP * ^. ALPHA
> state=.(nstate*-.accept)+state*accept
> state;>:index
> )
> And I call it e.g. by:
> f^:n (g0;0)
>
Jan:
If you want to get rid of explicitly mentioning index when you call the
function, I suggest the following, which allows you to get your result as
>{: F^:n (< g0)
First modify f so that index is a left hand argument and state is an
unboxed right hand argument. Then define a verb F which operates on
g0;(f g0);...;(f^:(n-1) g0)
by
F=:3 : 'y; (<:#y) f > {: y'
This appends the next iterate, while supplying index as the argument to f.
F keeps track of index by actually retaining the prior iterates. I
imagine that your images might be quite big. You can also count using
empty boxes except for the last:
F=:3 : 0
index=:<:#y
last=:>{:y
(}:y),a:,< index f last
)
Best wishes,
John
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