% UDMP
% L.Linares 2008
% For a second order differential equation with 
% complex conjugate eigenvalues with real part
% "sigma" and imaginary part "omega", and knowing
% the initial conditions:
%   yo = initial value of the function of time f(0).
%   yo'= initial value of the derivative of f'(0).  
%   yf = final value of the function of time f(infin).
%   s  = "sigma"
%   w  = "omega"
% NOTE: In the code, * means multiply.
% It produces k1 and k2 so:
%  y(t) = k1.exp(s.t).sin(w.t+k2)+yf

<< "yo Dyo yf sigma omega" PROMPT
   ->  yo dyo yf s w
   <<  yo  yf  -  DUP  s  *
       dyo  SWAP  -
       w  /  ->  a  b
       <<  a  b  /  ATAN  DUP
           SIN  INV  a  *  SWAP
           "k2="  ->STR  SWAP + SWAP
           "k1="  SWAP + SWAP 
       >>
   >>
>>