function y = decay(t,m,more_args)
%
%  Calculate f(t) = exp(-t/tc)*cos(omega*t) if m=0
%  or its first, second, or third derivative if m=1,2,3
%
%  Inputs:
%     t = list of times
%     m = 0, 1, 2, or 3
%     more_args = [tc omega] = time constant, frequency
%
error(nargchk(3,3,nargin));
tc = more_args(1);
omega = more_args(2);
e = exp(-t/tc);
c = cos(omega*t);
s = sin(omega*t);
switch m
    case 0 %% get function value
        y = e.*c;
    case 1 %% get first deriv
        y = 
    case 2 %% get second deriv
        y = 
    case 3 %% get third deriv
        y = 
    otherwise
        error('Fourth and higher derivatives unsupported!');
end