function [ux,uy,vx,vy]=shear(index,alpha,beta,u,v)
%SHEAR - compute strain rate components
%
%   this routine calculates quantities used by visc grad and
%   viscosity2 to compute the viscosity
%
%   Usage:
%      [ux,uy,vx,vy]=shear(index,alpha,beta,u,v)

summation=[1;1;1];
ux=(u(index).*alpha)*summation;
uy=(u(index).*beta)*summation;
vx=(v(index).*alpha)*summation;
vy=(v(index).*beta)*summation;						
