Plotting a polynomial function with roots

4 Ansichten (letzte 30 Tage)
Christina Cruz
Christina Cruz am 23 Okt. 2016
Kommentiert: Robert am 23 Okt. 2016
Hi there! I have barely have an idea of what to do with MatLab as of now and my professor pretty much leaves us to do the problems on our own without even teaching the basics first.
He gave us this problem: plot the function showing its roots. Label the roots r1, r2, etc.
f(x) = (x^3) - 10/((2-x)^2) + 25
i got one root through the fixed point iteration method which is roughly 1.3997 but i don't know how to plot this. Any help would be highly appreciated. Thanks in advance!
  1 Kommentar
Robert
Robert am 23 Okt. 2016
Bearbeitet: Robert am 23 Okt. 2016
Please don't forget to accept the answer Thanks!
syms x
f = (x^3) - 10/((2-x)^2) + 25 % Original function
%same function but rearranged
%Matlab needs to rearrange the function to be in the form of a polynomial
f_rearranged = x^5 -4*x^4 + 4*x^3 +25*x^2 -100*x+90
% Collect the coefficients in decending order
[My_coeffs,~] = coeffs(f_rearranged,x)
roots(My_coeffs) %Get the roots

Melden Sie sich an, um zu kommentieren.

Antworten (1)

Andrei Bobrov
Andrei Bobrov am 23 Okt. 2016
syms x
f = x^3 - 10/(2-x)^2 + 25
[n,~] = numden(f);
[c,~] = coeffs(n);
your_roots = roots(double(c));
your_roots = your_roots(imag(your_roots)==0)
  1 Kommentar
Robert
Robert am 23 Okt. 2016
Why are you removing imaginary roots? The answer is incomplete

Melden Sie sich an, um zu kommentieren.

Kategorien

Mehr zu Spline Postprocessing finden Sie in Help Center und File Exchange

Community Treasure Hunt

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

Start Hunting!

Translated by