in gaussian membership function from what value of signal the mean is subtracted?

Question

pinak parida 2013-12-16

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https://ww2.mathworks.cn/matlabcentral/answers/109904-in-gaussian-membership-function-from-what-value-of-signal-the-mean-is-subtracted

评论： Image Analyst 2014-1-5

for i=1:n
        A(i)=exp(-0.5*((x-c(i))./s(i)).^2);
end

where

x=sin(2*pi*t)
t=1:.3:10
n=length(x)
c=.4*ones(1,n) %mean
s=.4*ones(1,n) %variance

for each iteration what is the value of x from which mean is subtracted ?

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Answer 1

Image Analyst 2013-12-19

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https://ww2.mathworks.cn/matlabcentral/answers/109904-in-gaussian-membership-function-from-what-value-of-signal-the-mean-is-subtracted#answer_118877

编辑：Image Analyst 2013-12-19

在 MATLAB Online 中打开

It's all values of x. x is an array and if you don't specify an element, like x(i), then it does ALL elements. So it won't work because you'd be trying to stuff a whole vector into a single element of A. I'd say that you probably want x(i) instead of x.

Try it this vectorized way instead:

t=1:.3:10
x=sin(2*pi*t)
n=length(x)
c=.4*ones(1,n) %mean
s=.4*ones(1,n) %variance
A = exp(-0.5*((x-c)./s).^2)

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pinak parida 2013-12-31

编辑：pinak parida 2014-1-2

在 MATLAB Online 中打开

    %fuzzy logic inference system
clc
clear
close all 
% desired signal creation
yd1=-.1;
yd0=-.07;
u3=0;
u2=0;
u1=0;
u0=0;
for t=1:1000
    if t<250
        u(t)=sin(pi*t/25);
    elseif t<500 && t>249
        u(t)=1;
    elseif t<750 && t>499
        u(t)=-1;
    else
        u(t)=0.3*sin(pi*t/25)+0.1*sin(pi*t/32)+0.6*sin(pi*t/10);
    end
end
figure(1)
plot(u)
yd(1)=0.72*yd0+0.025*yd1*u1+0.01*(u2)^2+0.2*u3;
yd(2)=0.72*yd(1)+0.025*yd0*u0+0.01*(u1)^2+0.2*u2;
yd(3)=0.72*yd(2)+0.025*yd(1)*u(1)+0.01*(u0)^2+0.2*u1;
yd(4)=0.72*yd(3)+0.025*yd(2)*u(2)+0.01*(u(1))^2+0.2*u0;
for t=4:999
    yd(t+1)=0.72*yd(t)+0.025*yd(t-1)*u(t-1)+0.01*(u(t-2))^2+0.2*u(t-3);
end
%let us consider 3 input i.e 'x1,x2,x3';so m=j=3
%again each input is fed to 'n=i'number of MF,
%input signal creation
m=3;
n=length(yd);
for j=1:1:m
    for t=1:1000
        if t<250
            x(t)=sin(pi*t/25);
        elseif t<500 && t>249
            x(t)=1;
        elseif t<750 && t>499
            x(t)=-1;
        else
            x(t)=0.3*sin(pi*t/25)+0.1*sin(pi*t/32)+0.6*sin(pi*t/10);
        end
    end
   end 
    figure(1)
plot(x)
U=.1;          %learning parameter
c=0.4*ones(m,n); %mean of guassian mf
s=0.5*ones(m,n); %variance of gaussian mf  
%defining weight
W =0.4*ones(1,n); %weight of LF
% generating MF
q=30;
while(q)
for j=1:1:m
    for i=1:1:n
        %gaussian MF---- A(m,n)=exp(-((x(m)-c(m,n)/s(m,n))^2)
        A(j,:)=exp(-0.5*((x(j)-c(j,:))./s(j,:)).^2);
    end
end
    for i=1:1:n
    for j=1:1:m
        f(i)=min(A(:,i));          %f(i)=min(A(j,i))
        y(i)=sum(W(i)*(x(j)));     %y(i)=sumation j=1 to j=m (w(i)*x(j))
    end
    %output of fuzzy system
    %p=sumation i=1 to i=n (f(i)*y(i))/sumation i=1 to i=n (f(i))
    p(i)=sum(f(i)*y(i))/(sum(f(i))); 
    e(i)=yd(i)-p(i);   %error
    for j=1:1:m
    % updation rule
    W(i) = W(i)+U*e(i)*x(j);
    c(j,:) = c(j,:) + 0.5*e(i)*exp(-(x(j)-c(j,:)./s(j,:)).^2).* (x(j)-c(j,:)./(s(j,:).^2));
    s(j,:) = s(j,:) + 0.5*e(i)*exp(-(x(j)-c(j,:)./s(j,:)).^2).*(x(j)-c(j,:)).^2./((s(j,:)).^3);
end
end
%calculation of mse
p1=(sum(p)/(31));
MSE((31)-q)=sqrt(sum(e.^2)/sum((yd-p1).^2));
q=q-1;
end
figure(3)
plot(yd)
hold on
plot(p,'r')
hold on
plot(e,'g')
figure(4)
plot(MSE,'k','linewidth',2)

sir, i wrote this program for neuro-fuzzy system and got output. the error is decreasing with increase in iteration. BUT with changing the updation equation of mean(c)and variance(s) the output and mse does not change. so i cann't conclude whether program is CORRECT or NOT.

pinak parida 2014-1-5

sir , do you know anyone i can contact?

thankyou

Image Analyst 2014-1-5

There is a fuzzy logic toolbox, though I don't recall seeing a lot of fuzzy questions here. You can try rephrasing your question, listing "Fuzzy Logic Toolbox" in the product list, and making the title something like "Need help with Fuzzy Logic program" to see if any fuzzy experts here answer you. The Mathworks tech support line won't help with algorithm development, only things like errors, syntax, and other purely MATLAB-related stuff like that.

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