function y = int_yp(t,yp)
%INT_YP  Get position from list of velocities

%   Dale E. Gary 
%   $Revision: 1.0 $  $Date: 2008/09/01 13:42:00 $

n = length(t);
y = yp;
y(1,:) = [0 0];
for i=1:n-1
   dt = t(i+1)-t(i);
   dy = yp(i,:)*dt;
   y(i+1,:) = y(i,:)+dy;
end
y = y(1:n-1,:);