I tried to carry out a summation in 'for loop' which has symbolic variable in it. but it is showing some errors. I am attaching my script file. Please tell me where I am getting wrong.
MATLAB: ‘for loop’ summation containing symbolic variable
for loopsummation
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Hi,
you can use this script:
x0 = [12 3];x = lsqcurvefit(@(x,t)equation_fit(x,t),x0,t,S)S_calculated = equation_fit(x,t);plot(t,S,t,S_calculated)function S_calc = equation_fit(x,t)n = 1:250; % Number of sumations
a = 1; % define a
w2n = n.^2.*pi^2./4000; % Definition of omega_n_squared
% Fitting values
Cs = x(1);k = x(2);% Determine function
sum_parts = ((1-(-1).^n)./(n.^2)).*(exp(-w2n.*t)+... (k.*(1-(1+w2n.*t).*exp(-w2n.*t)))./(w2n+k.*(1-exp(-w2n.*t))));S_calc = 1 + a.*Cs.*(1 - (4/pi^2 .* sum(sum_parts,2)));endBut the resulting fit appears not to be a very good result to me:
Note that the last two lines of your data file contain invalid informations - i deleted them and attached the needed .mat-file to this answer, so that if you load the .mat-file to workspace you can execute the script and check the results by yourself. The result of sum_parts is a matrix with 89425x250 (number of samples of S(t) x n). In the second step the sum is build, so that you sum up from n=1...250 and the result is the S_calc with the needed dimenstion of 89425x1. This is the way you can solve this summation problem for curve fitting in Matlab.
Best regards
Stephan
You don't need the clear:
clear Sum_err;Sum_err = 0;Reinitialize Tp and Peak as well:
for k = 1:... Sum_err = 0; Tp = 0; Peak = 0; ...You also don't need to declare them outside of the loop.
Best Answer