function beta=betrsh(r1,r2,rv1,rv2,gamma)
%  calculate coagulation kernel for shear use rectilinear kernel. 
%  input - r1,r2 radius  cm 
%          gamma   shear in 1/s
%  output- beta coagulation kernel
%                         11 jy 93
global ratrirg

beta=1.3*gamma*(ratrirg*(r1+r2)) .^ 3;

