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% forcetrapstep.m
% Forced trapstep.m
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function y = forcetrapstep(t,x,h,d, force)
%one step of the trapezoid method
z1=forceydot(t,x,d, force);
g=x+h*z1;
z2=forceydot(t+h,g,d, force);
y=x+h*(z1+z2)/2;