Evaluate in a single value a function matrix

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JORGE ORDOÑEZ CARRASCO
评论： JORGE ORDOÑEZ CARRASCO 2020-12-29
Hi i have a to program Newton Raphson in many variables so for example: If i have a function
just like
It is known the Jacobian of f will return in this case a matrix of 2x2. I need to evaluate in a value for example u1=1 and u2=2. But f(1,1) obviously doenst work, i need to evaluate numerically this function and its jacobian and extend this for many variables above 2. By the way the jacobian is:
As you can see for example matrix A(1,1) returns element not a value so how can i evaluate a matrix and a vector in a known number without using x=rand(2,1), x(1),x(2) cause for many variables this will be more dificult to do it.
Thank you

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回答（1 个）

Walter Roberson
Walter Roberson 2020-12-29
Ran in:
Use the Symbolic Toolbox to build the equations. Then use matlabFunction with the 'vars' option passing in a cell array that contains a single entry that is the vector of variable names. matlabFunction will then generate an anonymous function with all of the variables extracted from a single vector of inputs.
syms u1 u2
f = [exp(u1)-cos(u2); exp(u2)-u1^2];
fh = matlabFunction(f, 'vars', {[u1, u2]})
fh = function_handle with value:
@(in1)[-cos(in1(:,2))+exp(in1(:,1));exp(in1(:,2))-in1(:,1).^2]
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Walter Roberson
Walter Roberson 2020-12-29
That is not my suggestion. I specifically said that you need to use the vars option with {} and I gave an example to emphasize what hasto be done .
JORGE ORDOÑEZ CARRASCO
JORGE ORDOÑEZ CARRASCO 2020-12-29
Thank you i realized it wasnt your suggestion i just did it again and it work.Thank you so much

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