Using fsolve in another fsolve mfile

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Minhyeon 2014-3-16

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https://ww2.mathworks.cn/matlabcentral/answers/121813-using-fsolve-in-another-fsolve-mfile

编辑： Minhyeon 2014-3-16

Hello all.

I am dealing with the following function such that:

f(x1(theta), x2(x1(theta))) = 0

where x2 is a (implicit) function of x1.

To solve the above equation, I made a code as follows:

============================================================================

y = fsolve(@(theta) myfun1(theta), x0)

where myfun1 is as follows:

function f = myfun1(theta)

x1 = log(3 * theta ^2 + 2 * theta ^3)

x2 = fsolve(@(x) myfun2(x,x1), x00, x1)

f = x1 + x2 - 10

and, finally, myfunc2 is written as follows:

function g = myfun2(x1)

g = log(x1 + x^2 - 10)

============================================================================

The thing is that I need to use fsolve in another function file that is also using fsolve since x2 is implicitly defined by x1.

However, whenever I run this mfile, then I face the following error message.

============================================================================ Warning: Struct field assignment overwrites a value with class "double". See MATLAB R14SP2 Release Notes, Assigning Nonstructure Variables As Structures Displays Warning, for details. ============================================================================

I strongly suspect that there is a problem in the mfile that uses fsolve twice.

Would you please make a comment on this? I sincerely appreciate all your answers.

Best,

Min