fitting a certain function up to a certain x-value

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Ahmed Elsherif
Ahmed Elsherif 2020-2-26
评论： Ahmed Elsherif 2020-2-26
Hello,
I have data in a two coulmns-excel file and I load them then I perform a fitting using a defined equation. I need to perform the fitting until a user defined value of x-axis. To have an equal length of x and y, I tried to look for the y value corresponding to the given x value. The code is:
dataset = xlsread('input.xlsx');
E=dataset(:,1);
F3g=dataset(:,2);
%Equation
f = @(x,Edata)(x(1)+(x(2)-x(1))*exp(-0.5*(Edata/x(3)).^x(4)))./(1+(Edata/x(5)).^1.6)+x(6)*((x(7)-x(8))./(Edata/x(9))+x(8));
x0 = [0 0 0 1 1 1 0 1 0];
Ev=getappdata(0,'edit3'); % this is an editable value by user
Z=F3g(E==Ev); % I try to get the value of F3g corresponding to Ev to have equal lengths
options = optimoptions('lsqnonlin','Display','iter');
[x,resnorm,~,exitflag,output] = lsqcurvefit(f,x0,E(1:Ev),F3g(1:Z),[],[], options) % fitting
1-It does not work and it shows the error;
Error using ==
Matrix dimensions must agree.
2-Also, If I set manually the number of column of F3g corresponding to the given value of Ev, e.g.,
[x,resnorm,~,exitflag,output] = lsqcurvefit(f,x0,E(1:Ev),F3g(1:19),[],[], options) % fitting
it shows the following error!
Error using :
For colon operator with char operands, first and last operands must be char.
it works only with
[x,resnorm,~,exitflag,output] = lsqcurvefit(f,x0,E(1:19),F3g(1:19),[],[], options) % fitting
But without using Ev while I need to use it. Any help or hints?
Thanks in advance

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