gusucode.com > 模糊控制工具箱 fuzzy logic toolbox源码程序 > fuzzy/fuzzy/zmf.m
function y = zmf(x, params) %ZMF Z-shaped curve membership function. % ZMF(X, PARAMS) returns a matrix which is the Z-shaped % membership function evaluated at X. PARAMS = [X1 X0] is a 2-element % vector that determines the break points of this membership function. % When X1 < X0, ZMF is a smooth transition from 1 (at X1) to 0 (at X0). % When X1 >= X0, ZMF becomes a reverse step function which jumps from 1 % to 0 at (X0+X1)/2. % % For example: % % x = 0:0.1:10; % subplot(311); plot(x, zmf(x, [2 8])); % subplot(312); plot(x, zmf(x, [4 6])); % subplot(313); plot(x, zmf(x, [6 4])); % set(gcf, 'name', 'zmf', 'numbertitle', 'off'); % % See also DSIGMF, EVALMF, GAUSS2MF, GAUSSMF, GBELLMF, MF2MF, PIMF, PSIGMF, % SIGMF, SMF, TRAPMF, TRIMF. % Roger Jang, 10-5-93, 7-14-94. % Copyright 1994-2002 The MathWorks, Inc. % $Revision: 1.17 $ $Date: 2002/04/14 22:21:49 $ if nargin ~= 2, error('Two arguments are required by ZMF.'); elseif length(params) < 2, error('ZMF needs at least two parameters.'); end x1 = params(1); x0 = params(2); if x1 >= x0, y = x <= (x0+x1)/2; return; end y = zeros(size(x)); index1 = find(x <= x1); if ~isempty(index1), y(index1) = ones(size(index1)); end index2 = find((x1 < x) & (x <= (x1+x0)/2)); if ~isempty(index2), y(index2) = 1-2*((x(index2)-x1)/(x1-x0)).^2; end index3 = find(((x1+x0)/2 < x) & (x <= x0)); if ~isempty(index3), y(index3) = 2*((x0-x(index3))/(x1-x0)).^2; end index4 = find(x0 <= x); if ~isempty(index4), y(index4) = zeros(size(index4)); end