请问这个function要怎么使用?
我目前一直卡在feval有错
我的f定义是
f(1)=15*x1+x2^2-4*x3-7;
f(2)=x1^2+10*x2-x3-18;
f(3)=x2^3-5*x3+7;
function如下
function [xv,it]=broyden(x,f,n,tol)
% Broyden's method for solving a system of n non-linear equations
% in n variables.
%
% Example call: [xv,it]=broyden(x,f,n,tol)
% Requires an initial approximation column vector x. tol is required
% accuracy. User must define function f, for example see page 115.
% xv is the solution vector, parameter it is number of iterations
% taken. WARNING. Method may fail, for example, if initial estimates
% are poor.
%
fr=zeros(n,1); it=0; xv=x;
%Set initial Br
Br=eye(n);
fr=feval(f, xv);
while norm(fr)>tol
it=it+1;
pr=-Br*fr;
tau=1;
xv1=xv+tau*pr; xv=xv1;
oldfr=fr; fr=feval(f,xv);
%Update approximation to Jacobian using Broydens formula
y=fr-oldfr; oldBr=Br;
oyp=oldBr*y-pr; pB=pr'*oldBr;
for i=1:n
for j=1:n
M(i,j)=oyp(i)*pB(j);
end;
end;
Br=oldBr-M./(pr'*oldBr*y);
end;