function y = yield(a,x)

% Yield Curve: Model
%
% Components of the input vector a:
% a(1) is the vertical dilation.
% a(2) is the horizontal dilation.
% a(3) is the horizontal shift.
% a(4) is the vertical shift.
% a(5) is the logarithm base.

y = a(1)*(log(a(2)*(x - a(3))))/log(a(5))+a(4);