solve non linear equation

2012 5 9
2 个回答
回答已采纳
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0 个投票

I wrote a function to find value of x (with 3 unknown) by solving 3 equations described in F
a= [5 8 4 4];
b= [4 15 3 3];
c= [12 12 2 2];
x0=[0 0 0];
function F = myfun2(x)
F = [sqrt((a(1)-x(1))^2+(a(2)-x(2))^2+(a(3)-x(3))^2)-(a(4)+4);
sqrt((b(1)-x(1))^2+(b(2)-x(2))^2+(b(3)-x(3))^2)-(b(4)+4);
sqrt((c(1)-x(1))^2+(c(2)-x(2))^2+(c(3)-x(3))^2)-(c(4)+4)];
Then I got the error after running this command
x=fsolve(@myfun2,x0)
??? Undefined function or method 'a' for input arguments of type 'double'.
Error in ==> myfun2 at 2
F = [sqrt((a(1)-x(1))^2+(a(2)-x(2))^2+(a(3)-x(3))^2)-(a(4)+4);
Error in ==> fsolve at 254
fuser = feval(funfcn{3},x,varargin{:});
Caused by:
Failure in initial user-supplied objective function evaluation. FSOLVE cannot
continue.
anyone have any idea that what problem I have? And how to solve it?
Thanks a lot!!!

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 采纳的回答

Walter Roberson
Walter Roberson 2012-5-9

0 个投票

The workspace of your function myfun2() does not have access to whichever workspace you defined "a" in.
Consider passing "a" and "b" in to the function myfun2(). Also consider defining myfun2() as a nested function with access to "a" and "b" as shared variables.

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The Anh
The Anh 2012-5-10
Thank you so much for your fast answer, highly appreciate :)

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The Anh
The Anh 2012-5-13

0 个投票

In case I work with a loop and a, b and c are variables and their values change in every loop. How can function "myfun2" have access to those variables?
How can I define mufun2() as a nested function with access to "a", "b" and "c" as share variables?

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