3.10 Continuous q-Jacobi

Definition. If we take , , and in the definition (3.1.1) of the Askey-Wilson polynomials we find after renormalizing

 

Orthogonality. For and we have

 

where

with

Recurrence relation.

 

where

and

Normalized recurrence relation.

 

where

q-Difference equation.

 

where

Forward shift operator.

 

or equivalently

 

Backward shift operator.

 

or equivalently

 

Rodrigues-type formula.

 

Generating functions.

 

 

 

Remarks. In [345] M. Rahman takes , , and in the definition (3.1.1) of the Askey-Wilson polynomials to obtain after renormalizing

 

These two q-analogues of the Jacobi polynomials are not really different, since they are connected by the quadratic transformation :

The continuous q-Jacobi polynomials given by (3.10.14) and the continuous q-ultraspherical (or Rogers) polynomials given by (3.10.15) are connected by the quadratic transformations :

and

If we change q by we find

References. [64], [163], [191], [193], [232], [234], [237], [322], [323], [345], [347], [348], [350], [371], [389].


Special cases


3.10.1 Continuous q-ultraspherical / Rogers

Definition. If we set , , and in the definition (3.1.1) of the Askey-Wilson polynomials and change the normalization we obtain the continuous q-ultraspherical (or Rogers) polynomials :

 

Orthogonality.

 

where

with

Recurrence relation.

 

Normalized recurrence relation.

 

where

q-Difference equation.

 

where

and

Forward shift operator.

 

or equivalently

 

Backward shift operator.

 

or equivalently

 

Rodrigues-type formula.

 

Generating functions.

 

 

 

 

 

 

 

Remarks. The continuous q-ultraspherical (or Rogers) polynomials can also be written as :

They can be obtained from the continuous q-Jacobi polynomials defined by (3.10.1) in the following way. Set in the definition (3.10.1) and change by and we find the continuous q-ultraspherical (or Rogers) polynomials with a different normalization. We have

If we set in the definition (3.10.15) of the q-ultraspherical (or Rogers) polynomials we find the continuous q-Jacobi polynomials given by (3.10.1) with . In fact we have

If we change q by we find

The special case of the continuous q-ultraspherical (or Rogers) polynomials equals the Chebyshev polynomials of the second kind defined by (1.8.31). In fact we have

The limit case leads to the Chebyshev polynomials of the first kind given by (1.8.30) in the following way :

The continuous q-Jacobi polynomials given by (3.10.14) and the continuous q-ultraspherical (or Rogers) polynomials given by (3.10.15) are connected by the quadratic transformations :

and

Finally we remark that the continuous q-ultraspherical (or Rogers) polynomials are related to the continuous q-Legendre polynomials defined by (3.10.32) in the following way :

References. [13], [15], [16], [31], [43], [44], [45], [53], [54], [55], [57], [64], [67], [94], [98], [99], [165], [185], [186], [187], [189], [191], [192], [193], [218], [232], [238], [239], [243], [258], [259], [278], [322], [323], [327], [350], [352], [356], [357], [358], [363], [364], [365], [370].


3.10.2 Continuous q-Legendre

Definition. The continuous q-Legendre polynomials are continuous q-Jacobi polynomials with :

 

Orthogonality.

 

where

with

Recurrence relation.

 

Normalized recurrence relation.

 

where

q-Difference equation.

 

where

and

Rodrigues-type formula.

 

Generating functions.

 

 

 

 

 

 

 

Remarks. The continuous q-Legendre polynomials can also be written as :

If we set in (3.10.14) we find

but these are not really different from those defined by (3.10.32) in view of the quadratic transformation

If we change q by we find

The continuous q-Legendre polynomials are related to the continuous q-ultraspherical (or Rogers) polynomials given by (3.10.15) in the following way :

References. [256], [262], [275], [279], [282].




Last modified on July 6, 1998