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How can I create expression or vector function handle, then plot it ?

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work wolf
work wolf on 8 Dec 2017
Commented: work wolf on 12 Dec 2017
How can I create vector function handle (anonymous function) with product a scalar value, then plot result. Clearly, I want to plot this formula
Let f(x,ym)= (1-exp(x-ym)/h); and
iX(x)=1/6.f(x,ym(1))+
7/6.f(x,ym(2))+
25/6.f(x,ym(3))+
43/6.f(x,ym(4));
iY(x)=1/5.f(x,ym(1))+
2/5.f(x,ym(2))+
14/5.f(x,ym(3))+
4/5.f(x,ym(4));
This code without loop but give me: ''Error using plot Conversion to double from sym is not possible''.
clear all;clc;a=0;b=2;n=3;h=(b-a)/n;ym=a:h:b;
X=[ 1/6, 7/6, 25/6,43/6]; % Data
Y=[ 1/5, 2/5, 14/5,14/5];
f=@(x,ym) (1-exp(x-ym)/h);
% with syms
syms x;
iX=f(x,ym(1:length(ym))).*X; % result iX= [f.1/6 , f.7/6 , f.25/6 , f.43/6]
iY=f(x,ym(1:length(ym))).*Y;
iFx= sum(iX);iFy=sum(iY); % result iFx= f.1/6 + f.7/6 + f.25/6 + f.43/6
x=ym;
plot(x,iFx,'r+');hold on;plot(x,iFy,'og');
Moreover, I tired to use a alternate codes with loop condition but the error persists as conversion to logical from sym is not possible.
% clear all;clc
% a=0;b=2;n=3;h=(b-a)/n;ym=a:h:b;
% %
% X=[ 1/6, 7/6, 25/6,43/6]; % Data
% Y=[ 1/5, 2/5, 14/5,4/5];
% %
% f=@(x,ym) (1-exp(x-ym)/h);
% %
% syms x %double(subs(x))
% iX=cell(1,length(ym));iY=cell(1,length(ym)); % cell, iX{k} and iY{k}
% % iX=zeros(1,length(ym));iY=zeros(1,length(ym));
% for k=1:length(ym)
% % iX(k) = f(x,ym(k)).*X(k);
% % iY(k) = f(x,ym(k)).*Y(k);
% iX{k} = @(x,k) f(x,ym(k)).*X(k);
% iY{k} = @(x,k) f(x,ym(k)).*Y(k);
% iX(x,k);
% end
% whos
% x=ym;
% plot(x,iX{:},'r:');hold on;plot(x,iY{:},'b--');
please, how can i fix it?
  2 Comments
work wolf
work wolf on 11 Dec 2017
Hello, Stephen Cobeldick :). I don't need to use a symbolic variable! I want to create a function with product data as scalar elements (constant), then plot it as I mentioned above, either codes are some attempts. I hope it's more clear now. If you have any idea. please, do not hesitate to present it.

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Answers (1)

Walter Roberson
Walter Roberson on 11 Dec 2017
plot(x,subs(iFx))
  1 Comment
work wolf
work wolf on 12 Dec 2017
@ Walter , Thanks .
subs() or matlabFunction(),
take too much time. In particular, at a long interval as ym=linspace(a,b,50000) or n large.

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