New to MATLAB - trying to write bisection method?
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Hello, I'm brand new to MATLAB and am trying to understand functions and scripts, and write the bisection method based on an algorithm from our textbook. However, I'm running into problems. Could anyone help me please?
Here is my code:
function [f] = Bisection(a,b,Nmax,TOL)
f = x^3 - x^2 + x;
i=1;
BisectA=f(a);
while i <= Nmax
p=a+(b-a)/2;
BisectP=f(p);
if BisectP == 0 || (b-a)/2 < TOL
disp('p');
end
i=i+1;
if BisectA*BisectP > 0
a=p;
BisectA=BisectP;
else
b=p;
end
end
disp('Method failed after num2str(Nmax) iterations, Nmax=', Nmax);
Thanks.
3 件のコメント
youcef mokrane
2020 年 11 月 9 日
編集済み: Walter Roberson
2020 年 11 月 9 日
x=4:4.7
f=tan(x)-x
a=4
b=4.7
fa=tan(a)-a
fb=tan(b)-b
n=1
n0=5000
while n<5000
p=(a+b)/2
fp=tan(p)-p
n=n+1
if fa*fp>0
a=p
else
b=p
end
end
Walter Roberson
2020 年 11 月 9 日
Why are you bothering to do x=4:4.7 ? The default increment for the colon operator is 1, so 4:4.7 is the same as 4:1:4.7 which is just going to be 4 .
Why are you assigning to n0 when you do not use it?
採用された回答
Walter Roberson
2013 年 12 月 15 日
編集済み: Walter Roberson
2013 年 12 月 16 日
Your line
f = x^3 - x^2 + x;
does not define a function. Try
f = @(x) x^3 - x^2 + x;
10 件のコメント
A_J Khan
2017 年 9 月 18 日
編集済み: Walter Roberson
2017 年 9 月 18 日
function p = bisection(f,a,b)
|
Error: Function definitions are not permitted in this
context.
I have this error with above code....???
Walter Roberson
2017 年 9 月 18 日
You can never define a function at the command prompt: you have to store a function inside a .m file; in this case, bisection.m
In versions up to R2016a you cannot store a function inside a script file (a .m file that does not start with the word "function" or "classdef"). That changed in R2016b.
その他の回答 (1 件)
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