Okay, I feel stupid asking this, but I have a question about a basic function, "mod".
My ported computations from CC become all wrong if I use Perl's built-in "%" operator. After a few trial and errors, it seemed like when CC mentions R = N mod M it's actually computing a fractional number. For example, 15.1 mod 4 would be 3.1. If I take that to be true, most of my computations work. However, now I'm having problems with taking a modulo of a negative value. Specifically, I'm trying to implement solar_longitude_after() (p.184) function -- but it chokes when the difference between $phi and solar_longitude($t) is a negative number to compute the value of $tau: $tau = $t + $rate * mod($phi - solar_longitude($t), 360); It seems like the output of mod() is expected to be something other than what I've been computing... (The reason I suspect that is because the solar terms that are generated by this function turns out wrong only if $phi - solar_longitude($t) is negative ). Does anybody know how this is supposed to work? I tried a bunch of things, but I just can't seem to get it right. Does anybody know how this *should* be done? TIA --d
