Re: Yet more While issues

[ikegami]

For clarity more than for speed,

my $offset = splice @cPosns, rand @cPosns, 1;

should be

my $offset = $cPosns[rand @cPosns];

and

while (1) {
   ...
   last;
}

should simply be

...

For speed, don't copy the zazb argument into a local variable. Access $_[3] directly.

A possible tweak:

push @cPosns, pos $zazb while $zazb =~ m{(?=c)}g;

might be faster as

push @cPosns, $-[0] while $zazb =~ m{c}g;

or maybe even

my $pos = -1;
push @cPosns, $pos while ($pos = index($zazb, 'c', $pos+1)) >= 0;

Benchmark and find out.

Which I just can't seem to get my head around to get it to work without throwing 'undefined value' warnings all over the place.

This will occur when 'c' doesn't occur in $zazb. Based on your first snippet, you want

sub popnum3 {
    my ( $x, $y, $z ) = @_;  # $_[3] is $zazb
    if ( $y == 0 ) {
        $aob[$x][0] = $initial * ( 1 + $z );
    }
    else {
        my @cPosns;
        push @cPosns, $-[0] while $_[3] =~ m{c}g;
        if (@cPosns) {
            my $offset = $cPosns[rand @cPosns];
            $aob[$x][$y] = $aob[$offset][ $y - 1 ] * ( 1 + $z );
        }
    }
    return $aob[$x][$y];
}

[Dandello]

I got it - at least it's stopped throwing warnings and it's a whole lot faster that what I had before.

Since popnum3 is called from inside an if/else

else {
   my $pos = -1;
   push @cPosns, $pos while ($pos = index($zazb, 'c', $pos+1)) >= 0;
   my $offset = $cPosns[rand @cPosns];
   $cell = sprintf '%.2f', popnum3( $x, $y, $copycop, $offset, );
}

then

sub popnum3 {
    my ( $x, $y, $z, $offset ) = @_;
    if ( $y == 0 ) {
        $aob[$x][0] = $initial * ( 1 + $z );
    }
    else {
        while (1) {
            $aob[$x][$y] = $aob[$offset][ $y - 1 ] * ( 1 + $z );
            last;
        }
    }
    return $aob[$x][$y];
}

So far it's looking good. Thanks

[ikegami]

What's with the useless while(1) { ...; last; } again?

[Dandello]

Habit

I'm still trying to get everything configured to work right - When I have the code set up like this:

else {
   my $pos = -1;
   push @cPosns, $pos while ($pos = index($zazb, 'c', $pos+1)) >= 0;
   my $offset = $cPosns[rand @cPosns];
   $cell = sprintf '%.2f', popnum3( $x, $y, $copycop, $offset, );
}

then

sub popnum3 {
    my ( $x, $y, $z, $offset ) = @_;
    if ( $y == 0 ) {
        $aob[$x][0] = $initial * ( 1 + $z );
    }
    else {
        while (1) {
            $aob[$x][$y] = $aob[$offset][ $y - 1 ] * ( 1 + $z );
            last;
        }
    }
    return $aob[$x][$y];
}

It's reiterating over the entire string for every single 'a' or 'c' which starts fast then slows to a crawl

When I move this section

 my $pos = -1;
   push @cPosns, $pos while ($pos = index($zazb, 'c', $pos+1)) >= 0;

above all the if/else's, to just under where $zazb is defined, then the $offset variable in

else {
   my $offset = $cPosns[rand @cPosns];
   $cell = sprintf '%.2f', popnum3( $x, $y, $copycop, $offset, );
}

becomes undefined when imported into popnum3.

So obviously I'm still missing something.

There is always at least 1 'c' in the string so that's not the problem.

[Dandello]

Back to square one I guess. This

 sub popnum3 {
    my ( $x, $y, $z ) = @_;  # $_[3] is $zazb
    if ( $y == 0 ) {
        $aob[$x][0] = $initial * ( 1 + $z );
    }
    else {
        my @cPosns;
        push @cPosns, $-[0] while $_[3] =~ m{c}g;
        if (@cPosns) {
            my $offset = $cPosns[rand @cPosns];
            $aob[$x][$y] = $aob[$offset][ $y - 1 ] * ( 1 + $z );
        }
    }
    return $aob[$x][$y];
}

only seems to work relatively short strings, but not when the string gets much more than 500 characters. Then it throws 'uninitialized value in $offset' errors which I'm guessing means the algorithm didn't find the one 'c' that had to be there.

I admit I'm at my wit's end here. This looks like it should work, but it doesn't. There is a 'c' in every row, so that's not the problem.

THIS works

sub popnum3 {
    my ( $x, $y, $z, $zazb ) = @_;
    if ( $y == 0 ) {
        $aob[$x][0] = $initial * ( 1 + $z );
    }
    else {
        while (1) {
            my $xda = int rand( $total + 1 );
            
            if ( substr( $zazb, $xda, 1 ) eq 'c' ) {
                $aob[$x][$y] = $aob[$xda][ $y - 1 ] * ( 1 + $z );
                last;
            }
        }
    }
    return $aob[$x][$y];
}

But takes about 5 seconds per row on the full array and since there's 8400 rows in the full run, that's about 12 hours.

Getting the run time down would be very helpful.

Thanks

[ikegami]

Then it throws 'uninitialized value in $offset' errors

I don't believe you when you say that snippet produced that warning.

Then it throws 'uninitialized value in $offset' errors which I'm guessing means the algorithm didn't find the one 'c' that had to be there.

No. If it doesn't find any 'c', it never uses $offset.

PS - Don't count out half the warning (not even counting the line number).