Here's a relevant quote from the OP at the start of this thread:

sub PolarToRect {
my($magnitude, $angle, $real, $complex);
#does it
return $magnitude . " _ " $angle;
}
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Now, can you tell us, clearly: is this subroutine supposed to return a rectangular form for a set of polar coordinates? If that's true, then the rectangular form being returned by this subroutine contains a " _ " (assuming that you fix the syntax error, which I mentioned in an earlier reply). So this is why pg is saying that this is the cause of the infinite loop -- this sub is returning rectangular coords that contain " _ ", and the constructComplex is assuming that this means the value is still in polar form. So it calls itself again (and again and again...)

update: Looking at your much longer (more detailed, more confusing!) reply to Grandfather, I see that the "running" version does not have this problem with " _ " in the "PolarToRect" sub. Your original post was just very misleading.