fuz_sign.m

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

function f = fuz_sign(f1)

% f=fuz_sign(f1)
%
% Test if the trapezoidel fuzzy intervall or triangular fuzzy 
% number is positive.
%  
% f1 = [xmin xmax m n alpha beta]  
% (ymin=0 und ymax=1 )
%
% A fuzzy interval is positive or negative, if all values of the 
% membershipfunction for positive or negative x-values are zero.
%
% f = 1 => positive.
% f = 2 => negative.
% f = 3 => not positive and not negative => multiplication,
%          division, inversion not possible.
%
% FSTB - Fuzzy Systems Toolbox for MATLAB
% Copyright (c) 1993-1996 by Olaf Wolkenhauer
% Control Systems Centre at UMIST
% Manchester M60 1QD, UK
%
% 8-Feb-1994
 
m = f1(3); n = f1(4); alpha = f1(5); beta = f1(6);

if (m-alpha) > 0;
  f=1; 
elseif (n+beta)  < 0;
  f=2; 
else f=3; end;