How do I plot the first four Chebychev polynomials in MATLAB?

How do I plot the first four Chebychev polynomials in MATLAB?

Answer 1

[Matt Fig]

Chebychev polynomials of the first or second kind?

Assuming the first kind, you can use the function handle method.

x = -1:.01:1;
C = @(x,n) cos(n*acos(x));  % Generating function.
plot(x,C(x,0),'r',x,C(x,1),'b',x,C(x,2),'k',x,C(x,3),'g')
axis([-1.2 1.2 -1.2 1.2])
legend({'Ch_0';'Ch_1';'Ch_2';'Ch_3'})

[Paulo Silva]

I presume that's the first order, see the dot? two dots would mean second order, I'm very sure :)

[Matt Fig]

Oh, I missed that!

[Paulo Silva]

nice code, I should have done that way, simple code and easy to plot more polynomials :) +1 vote

Answer 2

[Paulo Silva]

clf;hold all;
min=-1;max=1;points=1000;
x=linspace(min,max,points);
t0=1+0*x;
plot(x,t0)
t1=x;
plot(x,t1)
t2=2.*x.^2-1;
plot(x,t2)
t3=4.*x.^3-3*x;
plot(x,t3)
legend('t0=1','t1=x','t2=2*x^2-1','t3=4*x^3-3*x')