Index Position 1 is invalid. Newton's method program
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When I run the following code, I keep getting errors of either Index Position 1 is invalid or out of range subscript depending on my values for x0. Not sure what to do.
x0=[1,1,1,1,1,1,1,1,1]'; %enter estimates
I defined 9 functions (f1-f9)
J=sym(zeros(9));
for j=1:length(vars) %create Jacobian matrix
J(1,j)=diff(f1,vars(j));
J(2,j)=diff(f2,vars(j));
J(....
end
x=[x0];
for i=1:10
x(:,i+1)=x(:,i)-inv(J(x(1,i),x(2,i),x(3,i),x(4,i),x(5,i),x(6,i),x(7,i),x(8,i),x(9,i)))*f(x(1,i),x(2,i),x(3,i),x(4,i),x(5,i),x(6,i),x(7,i),x(8,i),x(9,i))'; %solve for x
end
采纳的回答
Walter Roberson
2021-3-20
You are invoking J as if it is a function with 9 inputs. But it is not a function: it is a 9 x 9 array of symbolic expressions.
You should create
F = [f1, f2, f3, f4, f5, f6, f7, f8, f9];
Jmat = jacobian(F, vars);
J = matlabFunction(Jmat, 'vars', {vars});
x(:,i) - J(x(:,i))\f(x(1,i),x(2,i),x(3,i),x(4,i),x(5,i),x(6,i),x(7,i),x(8,i),x(9,i))
and easier yet would be if you used matlabFunction() to turn f (whatever it is) into an anonymous function that accepted a vector of inputs.
What is the relationship between f and your f1, f2, and so on?
3 个评论
Hunter Crittenden
2021-3-20
Walter Roberson
2021-3-20
Jmat = jacobian(f, vars);
J = matlabFunction(Jmat, 'vars', {vars.'});
x(:,i) - J(x(:,i))\f(x(1,i),x(2,i),x(3,i),x(4,i),x(5,i),x(6,i),x(7,i),x(8,i),x(9,i))
Hunter Crittenden
2021-3-20
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