Apply a matrix to a function

Question

Johnny Yoon 2021-1-7

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/711078-apply-a-matrix-to-a-function

评论： Johnny Yoon 2021-1-25

采纳的回答： Deepak Meena

在 MATLAB Online 中打开

Dear Matlab experts,

I would like to apply a matrix into a function as follows.

clear all;
sizee = 1000;
syms 'T' [1 sizee]
T_syms = sym('T', [1 sizee]);
f = sym(zeros(sizee, sizee));
f(:,:) = T1 + T2 + T3 + T4 + ... + T1000; % This is just to make sample equations.
x_vars = (1:1000);
f_ftn (T_syms) = f;
solution = f_ftn(x_vars);

However, I got an error "Symbolic function expected 1000 input arguments but received 1." So, it seems I can't apply a matrix directly to a function. Is there any way that a matrix can be applied to a function? I can use matlabFunction as follows. However, it takes a way too long, like hours. Is there any way which takes a shorter amount of time? Thank you.

f_ftn02 = matlabFunction(f, 'Vars', {T_syms});

solution = f_ftn02(x_vars);

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Walter Roberson 2021-1-22

在 MATLAB Online 中打开

f_ftn02 = matlabFunction(f, 'Vars', {T_syms});

is the way. You could experiment, though, with

f_ftn02 = matlabFunction(f, 'Vars', {T_syms}, 'optimize', false);

As you are not writing to a file, I do not expect it to make any difference, but I saw a recent hint somewhere that some optimization is maybe now being done even when not writing to files, so you could try

Johnny Yoon 2021-1-25

Thank you again for your answer. It worked!

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Answer 1

Deepak Meena 2021-1-22

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/711078-apply-a-matrix-to-a-function#answer_603623

编辑：Deepak Meena 2021-1-22

在 MATLAB Online 中打开

Hi Johnny,

As far as my understanding goes , it is not possible. Because when you create a symbolic function indexed with a list of syms , the MATLAB will consider it as single entity.

But you can do something like this

clear all;
sizee = 1000;
syms 'T' [1 sizee]
T_syms = sym('T', [1 sizee]);
f = sym(zeros(sizee, sizee));
f(:,:) = T1 + T2 + T3 + T4 + ... + T1000; //or use sum(T_syms)
x_vars = (1:1000);
H(T_syms) = f;
cells = num2cell(x_vars);
H(cells{:});