This patch changes Complex#polar so that if its second argument (the
angle) is exact zero, then the result is a RealNum.  This makes it
consistent with how Complex#make works.

Otherwise you end up with the strange situation of:

#|kawa:1|# (make-polar 3 0)
3.0
#|kawa:2|# (= (make-polar 3 0) 3.0)
#t
#|kawa:3|# (real? 3.0)
#t
#|kawa:4|# (real? (make-polar 3 0))
#f
#|kawa:5|# (make-polar 3 0):class
class gnu.math.DComplex


N.B. (real? (make-polar 3 0)) returns #t in all the other Schemes I
checked (Gambit, Guile, MIT, and Racket), but doing so is not
required by RnRS.

--
Jamison Hope
The PTR Group
www.theptrgroup.com