www.gusucode.com > 模糊控制工具箱 fuzzy logic toolbox源码程序 > fuzzy/fuzzy/mf2mf.m
function [outParams,errorStr]=mf2mf(inParams,inType,outType,tol)
%MF2MF Translates parameters between membership functions.
% Synopsis
% outParams = mf2mf(inParams,inType,outType)
%
% Description
% This function translates any built-in membership function type into
% another, in terms of its parameter set. mf2mf tries to mimic the symmetry
% points for both the new and old membership functions. Occasionally this
% translation results in lost information, so that if the output parameters
% are translated back into the original membership function type, the
% transformed membership function will not look the same as it did
% originally.
% The input arguments for mf2mf are as follows:
% inParams: The parameters of the membership function you are transforming
% inType: a string name for the type of membership function you are
% transforming
% outType: a string name for the new membership function you are transforming
% to.
% Examples
% x=0:0.1:5;
% mfp1 = [1 2 3];
% mfp2 = mf2mf(mfp1,'gbellmf','trimf');
% plot(x,gbellmf(x,mfp1),x,trimf(x,mfp2))
%
% See also DSIGMF, GAUSSMF, GAUSS2MF, GBELLMF, EVALMF, PIMF,
% PSIGMF, SIGMF, SMF, TRAPMF, TRIMF, ZMF.
% Ned Gulley, 6-17-94
% Copyright 1994-2002 The MathWorks, Inc.
% $Revision: 1.24 $ $Date: 2002/04/14 22:22:43 $
yWaist=0.5;
yShoulder=0.90;
outParams=[];
errorStr=[];
if strcmp(inType,'trimf'),
lftWaist=yWaist*(inParams(2)-inParams(1))+inParams(1);
lftShoulder=yShoulder*(inParams(2)-inParams(1))+inParams(1);
rtShoulder=(1-yShoulder)*(inParams(3)-inParams(2))+inParams(2);
rtWaist=(1-yWaist)*(inParams(3)-inParams(2))+inParams(2);
elseif strcmp(inType,'trapmf') | strcmp(inType,'pimf'),
lftWaist=yWaist*(inParams(2)-inParams(1))+inParams(1);
lftShoulder=yShoulder*(inParams(2)-inParams(1))+inParams(1);
rtShoulder=(1-yShoulder)*(inParams(4)-inParams(3))+inParams(3);
rtWaist=(1-yWaist)*(inParams(4)-inParams(3))+inParams(3);
elseif strcmp(inType,'gaussmf'),
lftWaist=-abs(inParams(1))*sqrt(-2*log(yWaist))+inParams(2);
lftShoulder=-abs(inParams(1))*sqrt(-2*log(yShoulder))+inParams(2);
rtShoulder=2*inParams(2)-lftShoulder;
rtWaist=2*inParams(2)-lftWaist;
elseif strcmp(inType,'gauss2mf'),
lftWaist=-abs(inParams(1))*sqrt(-2*log(yWaist))+inParams(2);
lftShoulder=inParams(2);
rtShoulder=inParams(4);
rtWaist=abs(inParams(3))*sqrt(-2*log(yWaist))+inParams(4);
elseif strcmp(inType,'gbellmf'),
lftWaist=-inParams(1)*((1/yWaist-1)^(1/(2*inParams(2))))+inParams(3);
lftShoulder=-inParams(1)*((1/yShoulder-1)^(1/(2*inParams(2))))+inParams(3);
rtShoulder=2*inParams(3)-lftShoulder;
rtWaist=2*inParams(3)-lftWaist;
elseif strcmp(inType,'sigmf'),
if inParams(1)>0,
lftWaist=inParams(2);
lftShoulder=-1/inParams(1)*log(1/yShoulder-1)+inParams(2);
rtShoulder=2*lftShoulder-lftWaist;
rtWaist=2*rtShoulder-lftWaist;
else
rtWaist=inParams(2);
rtShoulder=-1/inParams(1)*log(1/yShoulder-1)+inParams(2);
lftShoulder=rtShoulder;
lftWaist=2*lftShoulder-rtWaist;
end
elseif strcmp(inType,'dsigmf'),
lftWaist=inParams(2);
lftShoulder=-1/inParams(1)*log(1/yShoulder-1)+inParams(2);
rtWaist=inParams(4);
rtShoulder=1/inParams(3)*log(1/yShoulder-1)+inParams(4);
elseif strcmp(inType,'psigmf'),
lftWaist=inParams(2);
lftShoulder=-1/inParams(1)*log(1/yShoulder-1)+inParams(2);
rtWaist=inParams(4);
rtShoulder=-1/inParams(3)*log(1/yShoulder-1)+inParams(4);
elseif strcmp(inType,'smf'),
lftWaist=yWaist*(inParams(2)-inParams(1))+inParams(1);
lftShoulder=yShoulder*(inParams(2)-inParams(1))+inParams(1);
rtShoulder=inParams(2);
if inParams(1)<inParams(2),
lftWaist=inParams(1);
rtWaist=2*inParams(2)-inParams(1);
else
lftWaist=2*inParams(2)-inParams(1);
rtWaist=inParams(1);
end
elseif strcmp(inType,'zmf'),
lftShoulder=inParams(2);
rtShoulder=inParams(2);
if inParams(1)<inParams(2),
lftWaist=inParams(1);
rtWaist=2*inParams(2)-inParams(1);
else
lftWaist=2*inParams(2)-inParams(1);
rtWaist=inParams(1);
end
else
% Input MF type is unknown
outParams=[];
errorStr=['Cannot translate from input MF type ' inType];
if nargout<2, error(errorStr); end
return
end
% We've translated into generalized coordinates, now translate back into
% MF specific parameters...
if nargin<4,
tol=max(eps, 1e-3*(rtShoulder-lftShoulder));
end
if strcmp(outType,'trimf'),
center=(rtShoulder+lftShoulder)/2;
% Assumes yWaist=0.5
outParams=[2*lftWaist-center center 2*rtWaist-center];
elseif strcmp(outType,'trapmf'),
% Assumes yWaist=0.5
outParams=[2*lftWaist-lftShoulder lftShoulder rtShoulder 2*rtWaist-rtShoulder];
elseif strcmp(outType,'pimf'),
% Assumes yWaist=0.5
outParams=[2*lftWaist-lftShoulder lftShoulder rtShoulder max(tol,2*rtWaist-rtShoulder)];
elseif strcmp(outType,'gbellmf'),
center=(rtShoulder+lftShoulder)/2;
a=max(tol,center-lftWaist);
b=2*a/(max(tol,lftShoulder-lftWaist));
outParams=[a b center];
elseif strcmp(outType,'gaussmf'),
center=(rtShoulder+lftShoulder)/2;
sigma=max(tol,(rtWaist-center)/sqrt(-2*log(yWaist)));
outParams=[sigma center];
elseif strcmp(outType,'gauss2mf'),
lftSigma=max(tol,lftShoulder-lftWaist)/sqrt(-2*log(yWaist));
rtSigma=max(tol,rtWaist-rtShoulder)/sqrt(-2*log(yWaist));
outParams=[lftSigma lftShoulder rtSigma rtShoulder];
elseif strcmp(outType,'sigmf'),
center=lftWaist;
a=-1/max(tol,lftShoulder-center)*log(1/yShoulder-1);
outParams=[a center];
elseif strcmp(outType,'dsigmf'),
lftCenter=lftWaist;
lftA=-1/max(tol,lftShoulder-lftCenter)*log(1/yShoulder-1);
rtCenter=rtWaist;
rtA=-1/max(tol,rtCenter-rtShoulder)*log(1/yShoulder-1);
outParams=[lftA lftCenter rtA rtCenter];
elseif strcmp(outType,'psigmf'),
lftCenter=lftWaist;
lftA=-1/max(tol,lftShoulder-lftCenter)*log(1/yShoulder-1);
rtCenter=rtWaist;
rtA=1/max(tol,rtCenter-rtShoulder)*log(1/yShoulder-1);
outParams=[lftA lftCenter rtA rtCenter];
elseif strcmp(outType,'smf'),
% Assumes yWaist=0.5
outParams=[2*lftWaist-lftShoulder lftShoulder];
elseif strcmp(outType,'zmf'),
% Assumes yWaist=0.5
outParams=[rtShoulder 2*rtWaist-rtShoulder];
else
% Output MF type is unknown
outParams=[];
errorStr=['Cannot translate to output MF type ' outType];
if nargout<2, error(errorStr); end
return
end
outParams=eval(mat2str(outParams,4));