# Can anyone tell me why I'm getting an error here? "xold=xnew;'' is giving me an error in this statement and I'm not sure why.

1 次查看（过去 30 天）
Brendan2023-2-22

clear all
close all
clc
% Problem 6.7
while (1)
fx=@(x) x.^3-6*x.^2+11*x-6.1;
% Using the Modified Secant Method
xold=3.5;
d=0.01;
% Iteration 1
xold=xnew;
xnew=xold-d*xold*fx(xold)/(fx(xold+d*xold)-fx(xold));
ea=abs((xnew-xold)/xnew)*100;
% Iteration 2
xold=xnew;
xnew=xold-d*xold*fx(xold)/(fx(xold+d*xold)-fx(xold));
ea=abs((xnew-xold)/xnew)*100;
% Iteration 3
xold=xnew;
xnew=xold-d*xold*fx(xold)/(fx(xold+d*xold)-fx(xold));
ea=abs((xnew-xold)/xnew)*100;
fprintf('The root using 3 iterations of Modified Secant Method is %8.4f with an approximate relative error of %6.3e\n',xnew,ea)
end
##### 1 个评论显示 无隐藏 无
Brendan 2023-2-22
I would also like to keep an argument attached to this code.

### 采纳的回答

KSSV 2023-2-22
These lines:
xold=3.5;
d=0.01;
% Iteration 1
xold=xnew;
xnew=xold-d*xold*fx(xold)/(fx(xold+d*xold)-fx(xold));
will obviously thrwo an error becuase xnew is a new variable and it is not defined. You need to either comment this line or you may need to move to the next line. After calculating xnew then save xnew to xold.

### 类别

Find more on Function Creation in Help Center and File Exchange

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by