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 commentaires
youcef mokrane
le 9 Nov 2020
Modifié(e) : Walter Roberson
le 9 Nov 2020
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
le 9 Nov 2020
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?
Réponse acceptée
Walter Roberson
le 15 Déc 2013
Modifié(e) : Walter Roberson
le 16 Déc 2013
Your line
f = x^3 - x^2 + x;
does not define a function. Try
f = @(x) x^3 - x^2 + x;
10 commentaires
A_J Khan
le 18 Sep 2017
Modifié(e) : Walter Roberson
le 18 Sep 2017
function p = bisection(f,a,b)
|
Error: Function definitions are not permitted in this
context.
I have this error with above code....???
Walter Roberson
le 18 Sep 2017
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.
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