% pulse4(t,r,T) is a periodic function of t with period T.
% For 0 < t < r, the function is a polynomial "spike" with
% area 1.  For r < t < T, the function is zero.  Outside
% of 0 < t < T, the function is defined to be periodic.
%
%
% Example:
%    t = 0:.005:4;
%    y = pulse4(t,.2,2);
%    plot(t,y)

function y = pulse4(t,r,T)
    t = mod(t,T);
    y = (t<r) .* (630*t.^4 .* (t/r-1).^4 ./ r.^5);