I am receiving this error "Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 5-by-5. Error in fminsearch (line 200) "

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Aynkaran 2022-10-3

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https://ww2.mathworks.cn/matlabcentral/answers/1816400-i-am-receiving-this-error-unable-to-perform-assignment-because-the-size-of-the-left-side-is-1-by-1

评论： Torsten 2022-10-3

I found this code on MATHWORKS site, which I am using find the order of a chemical reaction. But for some reason the code is not working. I am using MATLAB 2020 while the code was coded in MATLAB 2010. Would be much appreciated if someone would help me out.

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Aynkaran 2022-10-3

在 MATLAB Online 中打开

t=[1 2 3 4 5];

C=[200 134 120 110 89];

dispf (rorder(t,C))

function data = rorder(t,C)

%DATA = ORDERSEEK(T,C)

%Searches for the least-squares optimum solution for the reaction order

%from inputs time (t) and concentration (C). Outputs a struct (data) which

%contains the (1) reaction order (2) rate constant (3) rsquared value (4)

%half-life.

%t and C are vectors.

n = fminsearch(@(x) os_obj(t,C,x),0);

best_fit = polyfit(t,1./(C.^(n-1)),1);

k = best_fit(1)/(n-1);

rsquared = os_obj(t,C,n);

halflife = (2^(n-1) - 1)/...

((n-1)*k*C(1)^(n-1));

data.order = n;

data.k = k;

data.rsquared = -rsquared; %Revert back to positive value.

data.halflife = halflife;

end

function rsquared = os_obj(t,C,n)

%Order seek objective function. Returns the correlation coefficient for the

%line fit of the transformed data.

C_xform = 1./(C.^(n-1));

rsquared = -corr(t,C_xform).^2; %Negative, because we want the minimizer to maximize it.

%(c) February 8, 2010, Bradley James Ridder, University of South Florida.

%References:

%http://en.wikipedia.org/wiki/Rate_equation#Summary_for_reaction_orders_0.2C_1.2C_2_and_n

end

t=[1 2 3 4 5];
C=[200 134 120 110 89];
dispf (rorder(t,C))
function data = rorder(t,C)
%DATA = ORDERSEEK(T,C)
%Searches for the least-squares optimum solution for the reaction order
%from inputs time (t) and concentration (C). Outputs a struct (data) which
%contains the (1) reaction order (2) rate constant (3) rsquared value (4)
%half-life.
%t and C are vectors.
n = fminsearch(@(x) os_obj(t,C,x),0);
best_fit = polyfit(t,1./(C.^(n-1)),1);
k = best_fit(1)/(n-1);
rsquared = os_obj(t,C,n);
halflife = (2^(n-1) - 1)/...
           ((n-1)*k*C(1)^(n-1));
data.order = n;
data.k = k;
data.rsquared = -rsquared; %Revert back to positive value.
data.halflife = halflife;
end
function rsquared = os_obj(t,C,n)
%Order seek objective function. Returns the correlation coefficient for the
%line fit of the transformed data.
C_xform = 1./(C.^(n-1));
rsquared = -corr(t,C_xform).^2; %Negative, because we want the minimizer to maximize it.
%(c) February 8, 2010, Bradley James Ridder, University of South Florida.
%References:
%http://en.wikipedia.org/wiki/Rate_equation#Summary_for_reaction_orders_0.2C_1.2C_2_and_n
end 