function fvec=free_fall_forces(x,y)
	% free fall forces example
	% notice that physical meaning of the  independent variable 'x' is  time
	% we are solving y''(x)=-g, so the transformation to the canonical form is
	% y1=y; y2=y'
	% f=(y2,-g);

	g=9.8; % magnitude of the acceleration due to the free fall in m/s^2

	fvec(1)=y(2);
	fvec(2)=-g;
	% if we want to be compatible with Matlab solvers, fvec should be a column
	fvec=fvec.'; % Note the dot in .' This avoids complex conjugate transpose
end


