function k = derivs_multi_fin(x,y)
%calculate the derivative of the specified function.

k(1)=y(2);
k(2)=-0.5*y(2) - 7*y(1);

% k(1) = y(2);                %dT/dx = z
% k(2)=  0.1*y(1);            %dz/dx = m^2*(T-Tinf)
