Hmm.

Have to be careful with how the listserv processes certain character
combinations.

 > x = a.cos(t)
 > y = b.sin(t)
 >
 > for 0
 > substitute sqrt((D/2)^2 + b^2) for a.

the line 'for 0' started out as

for 0 (less than or equal to) t (less than or equal to) 2.pi

but the symbols got eaten.

Rob O'Connor