Find values that put equation to zero

Question

MARCO FORTI 2021-4-9

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/797502-find-values-that-put-equation-to-zero

评论： MARCO FORTI 2021-4-10

采纳的回答： Matt J

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In this model:

where all the variables are of dymension TX1, I need to find all the (T) values of gamma that put the equation to zero.

I tryed with the following code, but the program returns me all NAN, how can I fix the code to get it?

j=1; %increment level. The loop will work for j>1 as well.
for i=1:j:T;
fnc = @(gamma,C,S) 1./(1+gamma).*(C(i)-(S(i)*gamma)) - M(i);  % Model function
rn = @(gamma) norm(M - fnc(gamma,C,S)); % Residual norm
gamma0 = [15]; % Inizializzazione
[gamma, ResNorm] = fzero(rn, gamma0);  
end

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Answer 1

Matt J 2021-4-10

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https://ww2.mathworks.cn/matlabcentral/answers/797502-find-values-that-put-equation-to-zero#answer_671942

编辑：Matt J 2021-4-10

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gamma=nan(T,1);
j=1; %increment level. The loop will work for j>1 as well.
for i=1:j:T;
    
  ci=C(i); si=S(i); mi=M(i);
   
  fnc = @(gamma) 1./(1+gamma).*(ci-(si*gamma)) - mi;  
  gamma0 = 15; 
  
  [gamma(i), ResNorm] = fzero(fcn, gamma0);  
end

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Matt J 2021-4-10

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You may be initializing at a bad point. This works:

T=5;
[C,S,M]=deal(rand(T,1), rand(T,1), rand(T,1));
gamma=nan(T,1);
j=1; %increment level. The loop will work for j>1 as well.
for i=1:j:T;
    
  ci=C(i); si=S(i); mi=M(i);
   
  fnc = @(gamma) 1./(1+gamma).*(ci-(si*gamma)) - mi;  
  gamma0 = 15; 
  
  [gamma(i), ResNorm] = fzero(fnc, 0);  
end
gamma
gamma = 5×1
   -1.0000
    0.0302
    0.6949
    0.1094
   -0.4440