How to avoid dynamic variable names when I need to differentiate a function with lots of variables?

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Richárd Tóth 2019-9-20

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https://ww2.mathworks.cn/matlabcentral/answers/481332-how-to-avoid-dynamic-variable-names-when-i-need-to-differentiate-a-function-with-lots-of-variables

编辑： Matt J 2019-9-20

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Hello

Take my code for example:

n = 8;
syms f(x) distsq(x)
X=sym('x',[1 n-1]);
syms(X);
P = zeros(1,n)+0.1;
f(X) = sqrt(sum(X));
distsq(X) = sum((X-P(1:end-1)).^2) + (f-P(end)).^2;
grad_distsq = jacobian(distsq,X);
equations = grad_distsq == 0;
bounds = X > 0;
bounds = [bounds X<1];
equations = [equations bounds];
S = solve(equations,X);

The code runs fine, but I have

variables and it's troublesome to do operations with the solution structure S, which has

fields.

How should I remove dynamic names from the code?

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Matt J 2019-9-20

编辑：Matt J 2019-9-20

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What names do you want instead? You chose the names in the line

X=sym('x',[1 n-1]);

You could have used any other name, e.g.,

X=sym('frank',[1 n-1]);
>> S = solve(equations,X)
S = 
  struct with fields:
    frank1: [1×1 sym]
    frank2: [1×1 sym]
    frank3: [1×1 sym]
    frank4: [1×1 sym]
    frank5: [1×1 sym]
    frank6: [1×1 sym]
    frank7: [1×1 sym]