symbolic subs vectorized form

Question

Alexander 2019-5-22

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/463517-symbolic-subs-vectorized-form

回答： Alexander 2019-5-22

采纳的回答： Alexander

Hi there,

what does work is:

syms a b

vals = [4 5];

subs(a + b, [a, b], vals);

This returns 9 as expected.

What I'm trying to do is

syms a b

vals = [4 5; 6 7];

subs(a + b, [a, b], vals);

With the expected result of 9; 13.

Some technical framework:

The result does not need to be symbolic, if this does matter, I'm using vpa(subs(...)) anyway. The problem is: I have a symbolic solution of a large equation, where I want to replace parameters to gain the numeric value of the solution. The (symbolic) solution is also long and complicated, so that substituition in a loop lasts quite long.

Is there a way to define a vector with known parameters to pass it to subs/vpa (?) so that the numerical evaluation takes place only once?