Chapter 12: Q8-2P (page 562)
Find the norm of each of the following functions on the given interval and state the normalized function
Chapter 12: Q8-2P (page 562)
Find the norm of each of the following functions on the given interval and state the normalized function
All the tools & learning materials you need for study success - in one app.
Get started for freeSolve to get . If needed, see Chapter , Section 2. The given equation
Find the best (in the least squares sense) second-degree polynomial approximation to each of the given functions over the interval -1<x<1.
x4
Prove the least squares approximation property of Legendre polynomials [see (9.5) and (9.6)] as follows. Let f(x) be the given function to be approximated. Let the functions pl(x)be the normalized Legendre polynomials, that is, pl(x) = √(2l+1)/2 Pl(x) , so that
∫-11[pl(x)"]"2dx=1.
Show thatLegendre series for f(x)as far as the p2(x)term is
f(x)=c0p0(x)+c1p1(x) +c3p3(x) with c1 =∫-11f(x)pl(x) dx
Write the quadratic polynomial satisfying the least squares condition as b0p0(x)+b1p1(x)+b0p0(x)by Problem 5.14 any quadratic polynomial can be written in this form). The problem is to find b0, b1, b2so that I=∫-11[f2(x)+(b0-c0)2+(b1-c1)2+(b2-c2)2 -c02 -c12 -c22] dx
Now determine the values of the b's to make I as small as possible. (Hint: The smallest value the square of a real number can have is zero.) Generalize the proof to polynomials of degree n.
We obtained (19.10) forIt is, however, valid for, that is for. The difficulty in the proof occurs just after (19.7); we said that are finite at which is not true for.
However, the negative powers of x cancel if. Show this for by using two terms of the power series (12.9) or (13.1) for the function [see (13.3)].
Expand the following functions in Legendre series.
f(x) = P'n (x).
Hint: For I≥ n, ∫-11 P'n(x)Pl(x) dx=0 (Why?); for l<n, integrate by parts.
What do you think about this solution?
We value your feedback to improve our textbook solutions.