function y = weibull(alpha,lambda,t)
% WEIBULL y = weibull(alpha,lambda,t) Weibull density 
% Version of 1/24/91
% Density function for X ~ Weibull (alpha, lambda, 0)
% t is a matrix of positive evaluation points
% y is a matrix of the same dimensions as t
y = alpha*lambda*(t.^(alpha - 1)).*exp(-lambda*(t.^alpha));