function dX = linxhare_rhs(t,X,b)
%
%  This m-file evaluates the right-hand side
%  of the predator-prey ODE system
%
%  dX1/dt =  b(1)*X1 - b(2)*X1*X2
%  dX2/dt = -b(4)*X2 + b(3)*X1*X2

dX   =[b(1)*X(1)-b(2)*X(1)*X(2);
      -b(4)*X(2)+b(3)*X(1)*X(2)];