modquset.m

FISMAT accommodates different arithmetic operators, fuzzification and defuzzification algorithm, imp

function [mu_q,mu_c,S] = modquset(n)

% [mu_q,mu_c,S] = modquset(n)
%
% Creating a quadratic membership function mu_q and its complement mu_c on a universe S
% of n+1 elements. (Use an odd n to get an even number of states).
%
% mu_q(i+1) = 2*i^2 / n^2  for 0 <= i <= n/2 ,
% mu_q(i+1) = 1 - 2*(n-i)^2 / n^2 for n/2 < i < n .
%
% If invoked without lefthand arguments, a plot of mu_q its complement mu_c = 1-mu_q
% is plotted.
%
% FSTB - Fuzzy Systems Toolbox for MATLAB
% Copyright (c) 1993-1996 by Olaf Wolkenhauer
% Control Systems Centre at UMIST
% Manchester M60 1QD, UK
%
%       22-Aug-1995
%	Last change: 23/08/95
 
mu_q  = zeros(1,n+1); mu_c = mu_q; 
S  = 1:1:n+1;  
for i=0:n;
  if i <= n/2, mu_q(i+1) = (2*i^2)/(n^2); end;
  if (i > n/2) & (i <= n), mu_q(i+1) = 1-((2*(n-i)^2)/(n^2)); end;
end;
mu_c = 1-mu_q; % The complement.

if nargout==0,
  clf; plot(S,mu_q,'y-',S,mu_q,'yo',S,mu_c,'c-.',S,mu_c,'c*'); xlabel('universe of discourse'); ylabel('membership degree'); 
  set(get(gca,'xlabel'), 'FontSize', 8); set(get(gca,'ylabel'), 'FontSize', 8);
  axes(legend('yo','\mu_q','c*','\mu_c')); %set(gca,'FontSize',8);
end;