changing expression to function and then optimize the function

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Akhil
Akhil 2024-1-15
编辑： Matt J 2024-1-16
for the follwing expresson:
expr = expr + w(r2) * (sqrt((x(r1)-a(i))^2 + (y(r1)-b(i))^2)) - w(r1) * (sqrt((x(r2)-a(i))^2 + (y(r2)-b(i))^2));
I converted it to function by
syms expr x y w
ht = matlabFunction(expr);
Please suggest hw to minimize the above expression to find the values of multiple values of x,y and w.
I have data for the variable a,b,r1 and r2

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回答（1 个）

Matt J
Matt J 2024-1-15
编辑：Matt J 2024-1-15
Do not use syms or matlabFunction for a situation like this. Just write a plain function to compute the expression,
function expr=ht(xyw, a,b,r1,r2)
x=xyw(1);
y=xyw(2);
w=xyw(3)
expr=...
end
and then optimize it with, for example,
x0=... %initial guesses
y0=...
w0=...
xyw=fminunc(@(xyw) ht(xyw, a,b,r1,r2) , [x0,y0,w0])
  2 个评论
Akhil
Akhil 2024-1-16
is the following way is correct:
f = 0;
for i = 1:numel(a)
r1 = reg1(i);
r2 = reg2(i);
f = f + w(r2) * sqrt((x(r1)-a(i))^2 + (y(r1)-b(i))^2) - w(r1) * sqrt((x(r2)-a(i))^2 + (y(r2)-b(i))^2);
end
x0=0;
y0=0;
w0=10;
function f=ht(x,y,w)
x=zeros(1,26);
y=zeros(1,26);
w=zeros(1,26);
end
and kindly suggest how to perform the minimization
Matt J
Matt J 2024-1-16
编辑：Matt J 2024-1-16
Now that I see the whole loop, I don't quite understand what x(r1) refers to. Please give the sizes/dimensions of all the variables. In particular, aren't x,y,w scalar unknowns? If so, what does it mean to index x with r1?

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