Chebshev polynomial approximation

Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
1 reply · 2K views
sbashrawi
Messages
49
Reaction score
0

Homework Statement



Hi every body

I am triyng to find a polynolial approximation to the function: f(x)= (x+2)ln(x+2)
using the chebyshev polynomials,
the idea is to use MATLAB to find the coeefficients of the approximation poly.
using the comand double(int(...))
but this command doesn't give me any numerical value
what I got was:
>> int((x+2)*log(x+2)*(1-x^2)^-0.5,-1,1)
Warning: Explicit integral could not be found.
ans =
int((log(x + 2)*(x + 2))/(1 - x^2)^(1/2), x = -1..1)
>>
and if I use double(int(...)) an error message shows up
Any help pls

Homework Equations





The Attempt at a Solution

 
Physics news on Phys.org
Consider the substitution [itex]x=\cos(\theta)[/itex] and note that [itex]T_k(x) = \cos(k \,\theta)[/itex]. This should remove the singularity.