Re: Arbitrarily Many Nested Loops

Jacob JKW wrote:
This is what I have:

-------------
#!perl

for (my $i = 0; $i<=$n_ra->[0]; $i++) {
for (my $j = 0; $j<=$n_ra->[1]; $j++) {
for (my $k = 0; $k<=$n_ra->[2]; $k++) {
$prob_ra->[$i+$j+$k] += (
$f_raa->[0]->[$i] *
$f_raa->[1]->[$j] *
$f_raa->[2]->[$k] *
);
}
}
-------------
But that's obviously messy and more imprtantly I'd like to be able to
decide at run time to have how nested levels to go (probably be on the
order of 50 or 60). I assume that there's a canonical manner in which
this should be handled (using closures I'd guess) but I can't
sufficiently summarize my issue to make it Google-able.

Easy enough to do in perl:

my $index_var = 'aa';
my @var_names = map '$' . $index_var++, 0 .. $#$n_ra;

my $nested_loop = join( '',
map "\t" x $_
. 'for ( my '
. $var_names[ $_ ]
. ' = 0; '
. $var_names[ $_ ]
. ' <= $n_ra->[ '
. $_
. ' ]; '
. $var_names[ $_ ]
. "++ ) {\n", 0 .. $#$n_ra )
. "\t" x $#$n_ra
. '$prob_ra->[ '
. join( ' + ', @var_names )
. " ] +=\n"
. join( " *\n",
map "\t" x @$n_ra
. '$f_raa->[ '
. $_
. ' ]->[ '
. $var_names[ $_ ]
. ' ]', 0 .. $#$n_ra )
. "\n"
. join '', map "\t" x $_ . "}\n", reverse 0 .. $#$n_ra;

eval $nested_loop;



John
--
use Perl;
program
fulfillment
.

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