!
!   TITLE:  cc.mac (CALCULATION)
!
!
! Calculate the area between two concentric circles.
!
!   A = pi/4 * (OD^2 - ID^2)
!   
!
! cc,ParResult,OD,ID
!
!   where "OD" is the inside diameter
!         "ID" is the outside diameter
!         "ParResult" is the parameter name to assign the result to.
!
! Example:  cc,'foo',2,1
!
!   "foo" is a assigned the area between concentric circles with an
!   outer diameter of 2 and an inner diameter of 1.
!

*get,prkey_,active,0,prkey
/nopr

%arg1%=pi/4*(arg2**2 - arg3**2)

*if,prkey_,eq,1,then
    /go
*endif