Bioperl: making a random sequence

[Gatherer, D. (Derek)]

Morning all

I'm trying to make some 'control' DNA sequences......

srand();
for($x=1;$x<=1000000;$x++)
{
	$r = rand(1);
	if($r <= 0.25){ print "A"; }
	elsif($r <= 0.5){ print "C"; }
	elsif($r <= 0.75){ print "G"; }
	elsif($r <= 1.0){ print "T"; }
}

This spews out nonsense sequence but the proportions of bases are not equal.
A tends to be overrepresented at around 44% or so.  The others are
correspondingly reduced (sorry, I left the exact figures at home).  I've
checked that rand(1) really does generate numbers between 0 and 1, so why
the skew to larger numbers???

Do I need to tweak srand() somehow?

All help gratefuly appreciated.

Derek
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