Apply a matrix to a function

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Johnny Yoon
Johnny Yoon 2021-1-7
评论： Johnny Yoon 2021-1-25
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);
  2 个评论
Walter Roberson
Walter Roberson 2021-1-22
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
Johnny Yoon 2021-1-25
Thank you again for your answer. It worked!

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采纳的回答

Deepak Meena
Deepak Meena 2021-1-22
编辑：Deepak Meena 2021-1-22
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{:});

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