trap2l.m

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

function Lset = Trap2L(par,nol)

% Lset = Trap2L(par,nol)
%
% Converts a trapecoidal fuzzy set specified by the vector
% par = [a b c d] into a level set with nol levels. nol=4 would
% give the levels [1 0.75 0.5 0.25]. 
%
% The section from b to c describes the flat part of the
% trapecoid with level=1.
%
% FSTB - Fuzzy Systems Toolbox for MATLAB
% Copyright (c) 1993-1996 by Olaf Wolkenhauer
% Control Systems Centre at UMIST
% Manchester M60 1QD, UK
%
% O.Wolkenhauer 19 July 1996
% Last change 19 July 1996

Lset = ones(nol,3);

Lset(:,1) = (1/nol .* (nol:-1:1) )';

a=par(1); b=par(2); c=par(3); d=par(4);

Lset(1,2) = b;
Lset(1,3) = c;

level=Lset(:,1);

for i=2:nol,
  Lset(i,2) = (b-a)*level(i)+a;
  Lset(i,3) = -1*(d-c)*level(i)+d;
end;

if nargout==0,
  plot_set(par');
  hold on
    plot_Lset(Lset,'c');
  hold off
end;