Saving a matrix from a function file

Question

Aakar 2014-1-14

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https://ww2.mathworks.cn/matlabcentral/answers/112320-saving-a-matrix-from-a-function-file

评论： Mischa Kim 2014-1-14

Hi, I have created a function file and I need one of the values from the middle of that function file to plot it against time.

That function file is in a continuous loop, but when I save that one particular matrix it saves only the first value and plots a straight line against time. I cant figure out how I can create a plot with the varying value for that variable

This is the command that I am using to save that matrix. 'x', 'y' and 'z' are all variables. 'x' changes with time.

F = x*y + z;
save('F.mat','F');

Do i use a while loop or something else?

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Answer 1

Mischa Kim 2014-1-14

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编辑：Mischa Kim 2014-1-14

在 MATLAB Online 中打开

Could you share more of your code to see what exactly is happening, maybe as an attachment (see paper clip)?

Note, that in the above code F is a scalar, not a matrix. To make it a matrix (or vector) use (e.g.)

for ii = 1:n
   ...
   F(ii) = x(ii)*y + z;
   ...
end

assuming that x is a vector and y a scalar.

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Answer 2

David Sanchez 2014-1-14

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在 MATLAB Online 中打开

Use dot notation to operate with arrays:

x = rand(10,1);
y = rand(10,1);
z = rand(10,1);
F = x.*y + z;  % MIND THE DOT
save('F.mat','F');
F =
    0.5858
    0.6918
    0.8671
    0.1993
    0.1371
    0.9017
    1.2694
    0.5453
    1.2593
    0.2498

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Answer 3

Aakar 2014-1-14

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Thanks for your replies. I understand the overall concept of vectors and arrays. I am still not being able to save the different values of F as it is within a function file. Even if I run a 'for loop' in it, the value still will remain the same.

x is obtained from a ODE solver and it calls this function. So the value of x changes once every cycle. Therefore the value of F should change every cycle.

I am sorry, I wont be able to share more of the code as there are a lot variables and scalar values.