function beta=betcds(r1,r2,rv1,rv2,gamma)
%  calculate coagulation kernel for differential sed  use curvilinear kernel. 
%  input - r1,r2 radius- cm 
%  output- beta coagulation kernel
%                         11 jy 93
global ratrirg

rvec=[r1;r2];	% changed , to ;
rvvec=[rv1;rv2];
vsv=setvel(rvec,rvvec);
rless=min(rvec)*ratrirg;
beta=abs(vsv(1,:)-vsv(2,:)).*(.5*pi).*rless.^2;


