Error assignment of elements with ode15s

Question

Jeanine 2013-3-16

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/67484-error-assignment-of-elements-with-ode15s

I get the error "??? In an assignment A(I) = B, the number of elements in B and I must be the same."

I have tried debugging and evaluating the sizes of the left and right hand side of the culprit line but they are the same size (this is true for all values of t). When I evaluate the line in my workspace I do not have a problem. Below is the context of the problem:

Does anyone know why I am getting this error?

function dc=prob(t,c,A)
%system of odes with experimental data (A) passed to function
%odes are evaluated using ode15s at prescribed times from experimental data
dc=zeros(3,1);
V=2;
K=3;
km=4;
t_exp=xlsread('RawData.xlsx','raw data','E8:E47');    %experimental times 
ind=find(t_exp==t);     %find the time point being evaluated at this point
B=A(ind);    %locate the experimental data value corresponding to time point
dc(1)=km*c(3);
dc(2)=(V*B/(K + B ))*(c(1)/(km + c(1))); %THIS IS THE LINE THAT CAUSES THE ERROR
dc(3)=V+c(2);

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Answer 1

Walter Roberson 2013-3-17

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https://ww2.mathworks.cn/matlabcentral/answers/67484-error-assignment-of-elements-with-ode15s#answer_78927

ind=find(t_exp==t) is going to return ind as a logical vector that could have 0, 1, or multiple values set. Usually 0. If it does not happen to have exactly one true value, then B will not have exactly one value, and then the expression for dc(2) will be trying to store 0 or more-than-one values into a single scalar location dc(2)