What is this generalization of the Chebyshev polynomials?
up vote
5
down vote
favorite
For $varepsilon>0$ consider the tridiagonal matrix
$$L_{varepsilon}=begin{bmatrix}
0 & 1 & & & & & & \
1 & varepsilon & 1 & & & & & \
& 1 & 2 varepsilon & 1 & & & \
& & 1 & 3 varepsilon & 1 & & & \
& & & 1 & 4 varepsilon & 1 & & \
& & & & ddots & ddots & ddots & \
end{bmatrix}$$
with all blank entries equal to zero. A column vector $$Phi = begin{bmatrix} Phi_0 \ Phi_1 \ Phi_2 \ vdots end{bmatrix}$$ is an eigenvector $$L_{varepsilon} Phi = u Phi$$ iff the entries $Phi_h = Phi_{h}(u; varepsilon)$ satisfy a three-term recurrence $$Phi_{h-1} (u; varepsilon) + h varepsilon Phi_h(u; varepsilon) + Phi_{h+1}(u; varepsilon) = uPhi_{h}(u;varepsilon)$$ for $h geq 0$ with convention $Phi_{-1} = 0$, which is equivalent to
$$Phi_{h-1} (u; varepsilon) + (h varepsilon - u) Phi_h(u; varepsilon) + Phi_{h+1}(u; varepsilon) = 0.$$
Question: Can one identify the $Phi_h(u; varepsilon)$ with a known function, possibly a specialization or degeneration of the Gauss hypergeometric function?
As $varepsilon rightarrow 0$, the diagonal in $L_{varepsilon}$ disappears and $Phi_{h}(u; 0)$ are the Chebyshev polynomials. The recurrence above seems close to that of the Gegenbauer polynomials but is not exactly the same. Any help would be greatly appreciated!
special-functions hypergeometric-function orthogonal-polynomials chebyshev-polynomials
add a comment |
up vote
5
down vote
favorite
For $varepsilon>0$ consider the tridiagonal matrix
$$L_{varepsilon}=begin{bmatrix}
0 & 1 & & & & & & \
1 & varepsilon & 1 & & & & & \
& 1 & 2 varepsilon & 1 & & & \
& & 1 & 3 varepsilon & 1 & & & \
& & & 1 & 4 varepsilon & 1 & & \
& & & & ddots & ddots & ddots & \
end{bmatrix}$$
with all blank entries equal to zero. A column vector $$Phi = begin{bmatrix} Phi_0 \ Phi_1 \ Phi_2 \ vdots end{bmatrix}$$ is an eigenvector $$L_{varepsilon} Phi = u Phi$$ iff the entries $Phi_h = Phi_{h}(u; varepsilon)$ satisfy a three-term recurrence $$Phi_{h-1} (u; varepsilon) + h varepsilon Phi_h(u; varepsilon) + Phi_{h+1}(u; varepsilon) = uPhi_{h}(u;varepsilon)$$ for $h geq 0$ with convention $Phi_{-1} = 0$, which is equivalent to
$$Phi_{h-1} (u; varepsilon) + (h varepsilon - u) Phi_h(u; varepsilon) + Phi_{h+1}(u; varepsilon) = 0.$$
Question: Can one identify the $Phi_h(u; varepsilon)$ with a known function, possibly a specialization or degeneration of the Gauss hypergeometric function?
As $varepsilon rightarrow 0$, the diagonal in $L_{varepsilon}$ disappears and $Phi_{h}(u; 0)$ are the Chebyshev polynomials. The recurrence above seems close to that of the Gegenbauer polynomials but is not exactly the same. Any help would be greatly appreciated!
special-functions hypergeometric-function orthogonal-polynomials chebyshev-polynomials
add a comment |
up vote
5
down vote
favorite
up vote
5
down vote
favorite
For $varepsilon>0$ consider the tridiagonal matrix
$$L_{varepsilon}=begin{bmatrix}
0 & 1 & & & & & & \
1 & varepsilon & 1 & & & & & \
& 1 & 2 varepsilon & 1 & & & \
& & 1 & 3 varepsilon & 1 & & & \
& & & 1 & 4 varepsilon & 1 & & \
& & & & ddots & ddots & ddots & \
end{bmatrix}$$
with all blank entries equal to zero. A column vector $$Phi = begin{bmatrix} Phi_0 \ Phi_1 \ Phi_2 \ vdots end{bmatrix}$$ is an eigenvector $$L_{varepsilon} Phi = u Phi$$ iff the entries $Phi_h = Phi_{h}(u; varepsilon)$ satisfy a three-term recurrence $$Phi_{h-1} (u; varepsilon) + h varepsilon Phi_h(u; varepsilon) + Phi_{h+1}(u; varepsilon) = uPhi_{h}(u;varepsilon)$$ for $h geq 0$ with convention $Phi_{-1} = 0$, which is equivalent to
$$Phi_{h-1} (u; varepsilon) + (h varepsilon - u) Phi_h(u; varepsilon) + Phi_{h+1}(u; varepsilon) = 0.$$
Question: Can one identify the $Phi_h(u; varepsilon)$ with a known function, possibly a specialization or degeneration of the Gauss hypergeometric function?
As $varepsilon rightarrow 0$, the diagonal in $L_{varepsilon}$ disappears and $Phi_{h}(u; 0)$ are the Chebyshev polynomials. The recurrence above seems close to that of the Gegenbauer polynomials but is not exactly the same. Any help would be greatly appreciated!
special-functions hypergeometric-function orthogonal-polynomials chebyshev-polynomials
For $varepsilon>0$ consider the tridiagonal matrix
$$L_{varepsilon}=begin{bmatrix}
0 & 1 & & & & & & \
1 & varepsilon & 1 & & & & & \
& 1 & 2 varepsilon & 1 & & & \
& & 1 & 3 varepsilon & 1 & & & \
& & & 1 & 4 varepsilon & 1 & & \
& & & & ddots & ddots & ddots & \
end{bmatrix}$$
with all blank entries equal to zero. A column vector $$Phi = begin{bmatrix} Phi_0 \ Phi_1 \ Phi_2 \ vdots end{bmatrix}$$ is an eigenvector $$L_{varepsilon} Phi = u Phi$$ iff the entries $Phi_h = Phi_{h}(u; varepsilon)$ satisfy a three-term recurrence $$Phi_{h-1} (u; varepsilon) + h varepsilon Phi_h(u; varepsilon) + Phi_{h+1}(u; varepsilon) = uPhi_{h}(u;varepsilon)$$ for $h geq 0$ with convention $Phi_{-1} = 0$, which is equivalent to
$$Phi_{h-1} (u; varepsilon) + (h varepsilon - u) Phi_h(u; varepsilon) + Phi_{h+1}(u; varepsilon) = 0.$$
Question: Can one identify the $Phi_h(u; varepsilon)$ with a known function, possibly a specialization or degeneration of the Gauss hypergeometric function?
As $varepsilon rightarrow 0$, the diagonal in $L_{varepsilon}$ disappears and $Phi_{h}(u; 0)$ are the Chebyshev polynomials. The recurrence above seems close to that of the Gegenbauer polynomials but is not exactly the same. Any help would be greatly appreciated!
special-functions hypergeometric-function orthogonal-polynomials chebyshev-polynomials
special-functions hypergeometric-function orthogonal-polynomials chebyshev-polynomials
asked Nov 18 at 0:03
Swallow Tail
411
411
add a comment |
add a comment |
active
oldest
votes
active
oldest
votes
active
oldest
votes
active
oldest
votes
active
oldest
votes
Thanks for contributing an answer to Mathematics Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Some of your past answers have not been well-received, and you're in danger of being blocked from answering.
Please pay close attention to the following guidance:
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3002987%2fwhat-is-this-generalization-of-the-chebyshev-polynomials%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown