Error in using diff for derivative

4 ビュー (過去 30 日間)
Anantha Krishna B
Anantha Krishna B 2022 年 1 月 18 日
コメント済み: Torsten 2022 年 1 月 19 日
Hello
I am writing a function for calculating a root of a function using Newton's Method. In this i need to calculate value of derivative of the function. So I used diff but I am getting an error. I am thinking that the error is because diff only acts on symbolic functions and this somehow causes error. Is there any alternative way?
Below is my code
function [root] = Newton_rap_fun(a, error, f)
% function for newton's method
% a is the initial approximation, error is the error tolerance given by
% user
% f is the given function
while (true)
if (diff(f(a)) ~= 0)
b = a - f(a)/diff(f(a));
if (abs(b-a) <= error)
root = b;
break
end
else
root = a;
end
end
  3 件のコメント
Torsten
Torsten 2022 年 1 月 19 日
Numerical difference approximations exist also for derivatives of order n>1:
Or use symbolic maths and MATLAB's diff-command.

サインインしてコメントする。

回答 (1 件)

VBBV
VBBV 2022 年 1 月 19 日
t = f(a);
while (true)
if (gradient(t) ~= 0)
b = a - t./gradient(t);
if (abs(b-a) <= error)
root = b;
break
end
else
root = a;
end
end
check with this
  1 件のコメント
Torsten
Torsten 2022 年 1 月 19 日
f(a) is a scalar. "gradient" makes no sense in this case.

サインインしてコメントする。

製品


リリース

R2021b

Community Treasure Hunt

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

Start Hunting!

Translated by