Hi, I'm new

How can I solve a cubic equation using method of Taylor in MATLAB? for example this one: x^3+x^2-16*x=16. please, help me :) if you already have the similar task please send me or attach file. thanks

[Azzi Abdelmalek]

Hi, I'm new, can't be a title to your question

[Azzi Abdelmalek]

http://www.mathworks.com/matlabcentral/answers/8626#answer_11866

Answer 1

[Image Analyst]

Try using fzero() like this, all in an m-file called test3.m. It correctly gives a root of -1:

function test3
clc;    % Clear the command window.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;

% Plot the data
% Make 400 points along the x axis from -3 to +3.
x = linspace(-3, 3, 400);
yValues = x.^3 + x .^ 2 - 16 * x;
% Plot the function.
plot(x, yValues, 'b-', 'LineWidth', 2);
grid on;
title('y = x.^3 + x .^ 2 - 16 * x', 'FontSize', fontSize);

% Plot a line along the x and y axes.
hold on;
line(xlim, [0, 0], 'Color', 'k', 'LineWidth', 2); % Plot x axis.
line([0, 0], ylim, 'Color', 'k', 'LineWidth', 2); % Plot y axis.

% Plot a line at y = +16
line(xlim, [16, 16], 'Color', 'b', 'LineWidth', 2);

x0 = -2; % initial point
theRoot = fzero(@f, x0)

function y = f(x)
y = x.^3 + x .^ 2 - 16 * x - 16; % Subtract 16 so the function is zero at the root.

%

[kvk lord]

thank you :))

[Image Analyst]

I don't know what "The Method of Taylor" is. What is it? Who was he?

[kvk lord]

In this case you used the code which is already used in matlab. I need to write the similar algorithm "my algorithm/code", step by step, using method of Taylor. Do you know what I mean?

[Image Analyst]

No I don't. Did you see my last comment? All I've heard of is the "Taylor Series", which doesn't seem related to this at all. Again, I don't know what "The Method of Taylor" is. What is it? Who was he?

[kvk lord]

[kvk lord]

[kvk lord]

sorry for my bad English (

Answer 2

[Roger Stafford]

It’s a lot easier to do this one by hand and bypass matlab altogether:

x^3+x^2-16*x-16 = (x-4)*(x+4)*(x+1) = 0

which gives you its three possible solutions immediately: 4, -4, and -1. However, if you are determined to have the computer do it, use ‘roots’:

r = roots([1,1,-16,-16]);

[kvk lord]

I know how I can solve this without matlab but I want using Taylor's method