How to write a For function using values from a table ?

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Rami Altam
Rami Altam 2018-3-28
评论： Rami Altam 2018-3-28
My equation is:
y(1) = FOPT -(55930.4 - 330502.*x(1) - 3.18673E6.*x(2) + 344393.*x(3) + 471232.*x(4) + 1.58821E6.*x(5) - 156.186.*x(6));
I want to create a For function and substitute FOPT of a value from a table in the Matlab named FOPT.
Thank you.

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回答（1 个）

Walter Roberson
Walter Roberson 2018-3-28
y = NameOfTable.FOPT - (55930.4 - 330502.*x(1) - 3.18673E6.*x(2) + 344393.*x(3) + 471232.*x(4) + 1.58821E6.*x(5) - 156.186.*x(6));
All of the x references are scalars, so the expression in () is a scalar, and a scalar can be subtracted from a matrix without difficulty.
Note: if you are trying to fit parameters against a model, then unless you have strong constraints on your x values, there is not going to be a unique answer, since a change in any one of the x() values can be exactly compensated by a change in another value. For example an increase of 1 in x(1) can be exactly compensated by a decrease of 330502 / 156.186 = 2116.07954618212 in x(6) or an increase of 344393/330502 = 1.04203000284416 in x(3)
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Walter Roberson
Walter Roberson 2018-3-28
编辑：Walter Roberson 2018-3-28
FOPT_values = NameOfTable.FOPT;
num_FOPT = length(FOPT_values);
y = zeros(num_FOPT, 1);
for FOPT_idx = 1 : num_FOPT
FOPT = FOPT_values(FOPT_idx);
y(FOPT_idx) = FOPT -(55930.4 - 330502.*x(1) - 3.18673E6.*x(2) + 344393.*x(3) + 471232.*x(4) + 1.58821E6.*x(5) - 156.186.*x(6));
end
... But this is a waste of time, since you can use the simple code
y = NameOfTable.FOPT - (55930.4 - 330502.*x(1) - 3.18673E6.*x(2) + 344393.*x(3) + 471232.*x(4) + 1.58821E6.*x(5) - 156.186.*x(6));
This does substitute FOPT from the table named NameOfTable
https://www.mathworks.com/help/matlab/tables.html

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