Fortran - FORALL STATEMENT

Author

FORALL STATEMENT

jdturner

2006-10-30, 7:16 pm

Experts,

I have a recurring application need where I have many conditions to be
evaluated simultaneously, with only a single valid response. For
example, one might have the following code fragment:

forall( 1 = 1:n, all( mask=v-a(i) == 0 ) ) tmp(1) = i
ans: tmp(1)

I know that forall wants an array solution==> I have provided a
artifical array with one location being set equal to i. My question
is: (1) is there another way, (2) is this portable?

Jim Turner

Craig Powers

2006-10-30, 7:16 pm

jdturner wrote:
> Experts,
>
> I have a recurring application need where I have many conditions to be
> evaluated simultaneously, with only a single valid response. For
> example, one might have the following code fragment:
>
> forall( 1 = 1:n, all( mask=v-a(i) == 0 ) ) tmp(1) = i
> ans: tmp(1)
>
> I know that forall wants an array solution==> I have provided a
> artifical array with one location being set equal to i. My question
> is: (1) is there another way, (2) is this portable?

FORALL is, fundamentally, an array assignment statement, but it appears
to me that you're trying to turn it into a loop.

Since you're trying to find a single index i, I suspect that the most
efficient (and also least tortured) way to do what you want is to use a
vanilla DO loop to locate the correct index, save it, and EXIT out of
the loop.

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