3344
Inversion Formula For Fourier Jacobi Wavelet
Transform
C. P. Pandey and P. PhukanAbstract:- In this paper an inversion and Plancherel formula for Fourier-Jacobi wavelet transform are investigated. The Calderon’s reproducing formula for this wavelet transform is also obtained. Some applications associated with Calderon’s reproducing formula for Fourier-Jacobi convolution are given.
Index terms:- Calderon’s reproducing formula; convolution for Fourier-Jacobi operator; Fourier-Jacobi transform; Wavelet transform for Fourier-Jacobi operator.
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1.
INTRODUCTION
Integral transform involving special functions as kernels have been used by many authors for the construction of wavelets and wavelet transforms. Pathak and Dixit[10], Pathak and Pandey[8] have constructed Bessel wavelets and Laguerre wavelets by using the theory of Hankel transform and Laguerre transform. Wavelets on finite intervals involving solution of Sturm-Liouville system have been studied by U. Depczynski[11]. Fourier- Jacobi transform is another important transform for the construction of wavelet and wavelet transform. In this paper we describe a new construction of wavelets by using the theory of Fourier- Jacobi transform and inversion and Calderon’s reproducing formula are obtained.
2.
PRILIMINARIES
The generalized Legendre function P( , ) ( )x defined by equation (2.1), which is given below
/2
(1 ) 1
( , )( ) 1, ;1 ; ,
/2 2 2 2
(1 )( 1)
x x
P x F x R
x
where
, ; ;
F a b c z denotes the Gauss hypergeometric function is a
generalization of the Jacobi polynomial 1, .343p . It reduces
to the Jacobi polynomial P( , )( )x
n
forn, a non-negative
integer. Integral transforms with generalized Legendre functions as kernels have been investigated by Braaksma and Meulenbeld[1]. Theory and applications of these transforms can also be found in[3,5,6]. The convolution theory developed by Flensted-Jensen and Koornwinder[5] is basis for the present work.
The following normalized form will be used in the sequel.
R( , ) ( )x P( , ) ( )/x P( , ) (1),x R
(2.2)
Let ch t( ) denote cosh( )t and sh t( ) denote sinh( )t .Then set
( ) ( , ) ( 2 ) 1 ( ) 2
t R ch t
i
(2.3)
Moreover as in [7] we can also express
1 1
( , )( ) ( ) ( ), ( );1 ; ( )2
2 2
t t F i i sh t
(2.4)
Also, from [7] we know that ( )t is a solution of the initial value problem
1 ( ) ( ) ( ) 2 2 ( )
( )
d d
t u t u t u t
t dt dt
(2.5)
u(0) 1, u(0) 0
where
2 1 2 1
( ) (t et et)(et et) , 1 0
22(sht)21(cht)21.
Let ( )t be a Jacobi function of the second kind which is a
solution of (2.5) such that ( )t e(i )t[1o(1)] as t
. Thus
- 1-i 1
( ) ( ) , ;1 ;
2
2 2 ( )
i i
t t
t e e F i
sht
. (2.6)
One can show that
( ) c ( )t ( ) c(- )t ( )t (2.7)
where
( ) 2 ( ) ( 1) - 1 i
2 2
i i
c
i
Let p
L be the space of all those functions f on 0, such that
————————————————
• C.P.Pandey, Assistant Professor, Department of Mathematics at North Eastern Regional Institute of Science and Technology, India. E-mail: [email protected]
3345
1/
0
, 1
.
p
p p
f f d p
An inner product on L2 is defined by
, ( ) g(t) d (t) 0
f g f t
where
1/2
(2 )
dt t dt
(2.8)
For f L1 , the Fourier –Jacobi transform [7] of f is defined by
1
ˆ( ) (2 ) 2 ( ) ( ) ( ) ( ) ( )
0 0
f f t t t dt f t t dt
(2.9)
The inverse of (2.9) is given by
2 2
( ) (2 ) g ( ) ( )| ( )| g ( ) ( ) ( )
n
g t t c d t d
R R
(2.10)
Where d 21/2c 2d . As in [7] we define the convolution
( * )( ) ( ) ( ) ( , , ) ( ) ( ) 0 0
f g x f t g s K x s t dt d s
, (2.11)
where
1 2 1
2
2 ( 1) 1 2 3
(1,2,3) 2
1
1 2 3 2
cht cht cht K t t t
sht sht sht
, ; 1;1 2 2
B F
with
22 2
( 1) 2 ( 3) 1
, |1 2| 3 1 2 2 1cht2cht3
cht cht cht
B t t t t t
cht
(2.12)
and zero otherwise. Then the function K t t t
1 2 3, ,
satisfies thefollowing properties:
(i) K t t t
1 2 3, ,
is symmetric in all the three variables;(ii) K t t t
1 2 3, ,
0;(iii)
1 2 3, ,
(3) 1 0K t t t d t
.
Also it has been shown in [7] that
( ) 1 (2) (3) 1 2 3, , d 3 0
t t t K t t t t
(2.13)
Applying (2.10) to (2.13), we have
( ,1 2 3, ) ( ) 1 (2) (3) ( ) 0
K t t t t t t d
(2.14)
For 1 p 2 and 1 1 1
p q
define the strip
{
Dp i ℂ : | | (2/p-1) }, 1 0
.
From [7]we have followingLemma 2.1 Let 1 p 2, 1 1 1
p q
and f Lp( ) Then f( )
is holomorphic in Dp and for all 1Dp,
( ) || || || ||
f f p q
. (2.15)
If f L1( ), ( ) fˆ is continuous in D1 and for all D1
( ) 1
f f
(2.16)
In [7] if fLp( ) and g Lq , f g L* r then *
f grf p fq. (2.17)
Moreover, for f g, L1( ) we have
ˆ ˆ
( * ) ( )f gf( ) ( ) g (2.18)
For any f L2 ( ) , the following Parseval identity holds for the Fourier-Jacobi transform:
2 ˆ 2
( ) ( )
0 0
f t dt f d
(2.19)
3. FOURIER – JACOBI WAVELET
TRANSFORM
The Fourier – Jacobi translation [5] y off Lp( ) defined by
( ) , ( ) , , ( ),0 ,
0
f x f x y f z D x y z d z x y y
(3.1)
maps ( )x defined on the positive half of the real axis into
the function f x y( , )defined on the upper half of the positive half plane. y is also called generalized translation. In
terms of this translation convolution (2.11) can also be expressed as
( * ) 0
f g x yf y g y dy
. (3.2)
Using Hölder’s inequality it can be shown that
( )
f p f p
y L L
(3.3)
and the mapyyf is continuous for all
, [1, )
p
f L p .
The dilation 1
Dk is given by
( ) (1),1 0 1
Dk t k t k . (3.4)
Using the above translation and dilation the wavelet
, 2 1 x
k k
is defined as follows
( ) ( ) ( )
, 1
2 1 x 2D1 x 2 k x
k k k k k
(3.5)
Definition 3.1. Admissible Fourier-Jacobi wavelet.
3346
ˆ ( )2 ( ) 0
C d
, where ˆ( ) is the
Fourier-Jacobi transform of.
Definition 3.2. Continuous Fourier-Jacobi wavelet transform (FJWT)
For ( )tL2( ) and k2 1,k0 we define the continuous Fourier – Jacobi wavelet transform with respect to the Fourier- Jacobi wavelet ,
2 1t
k k
as follow
(2 1, ) ( ) 2 1, ( ), , ( ) 2 1
J k k Jf k k f t k k t
( ) , ( ) ( ) 2 1 0
f tk k t d t
(3.6)
( ) (1) ( ) 2
0
f t k k t dt
( ) (1) ( 2, , ) ( ) 0 0
f t k z K k t z dt dz
(3.7)
provided the integral is convergent. Since by (2.11) and (2.17) , ( )
2 1
p L k k
whenever Lp( ) , by Hölder’s inequality the integral (3.7) is convergent for f Lq( ), 1 1 1
p q
.
Theorem 3.1. If is an Fourier-Jacobi wavelet and f is a
bounded integrable function in L1( ) , then the convolution ( * ) f is an Fourier-Jacobi wavelet.
Proof:Since 2
2* ( ) ( ) ( ) ( ) ( )
0 0
f d x x y f y d y d x
2 2 1( ) f 2( )
L L
Hence *f( )L2( ) . Moreover
2 *
( ) *
0
f
C f d
2 2 ˆ ˆ
( ) 0
f d
2 ˆ 2
ˆ ( ) ( )
( )0
f d
L
Hence *f is a Fourier-Jacobi wavelet.
4.
BASIC PROPERTIES OF FJWT
Theorem 4.1. Let and be two wavelets and f g, be two functions belongs to L2 ( ) , then
(i) Linearity property:
J(fg k k)(1 2, )J( )(f k k1 2, )J( )(g k k1 2, ) Where and are any two scalars.
(ii) Shift property:
(Jf)(x)(k k1 2, ) (Jf)(k k1 2, )
Where is any scalar.
(iii) Scaling property: If c0 is any scalar, then the Fourier-Jacobi wavelet transform of the scaled
function f ( )x 1f
1c c c is
1 2 (J fc)(k k1 2, ) J f k,k
c c
(iv) Symmetry property:
( )(1 2, ) ( )( ) 1, 1 1 2
J f k k J f
k k
(v) Parity property:
(Jppf)(k k1 2, ) (Jf)
k1,k2
Where p is the parity operator defined by
( ) ( )
pf xf x .
Proof: The proof is the straight forward application of Fourier-Jacobi transform.
5.
PLANCHEREL
AND
PARSEVALS
FORMULA FOR FOURIER-JACOBI WAVELET
TRANSFORM:
This section describes important properties of the Fourier-Jacobi wavelet transform, such as the Plancherel, inversion formula and associated convolution first, we establish the following theorem.
Theorem 5.1 (Plancherel formula for Fourier-Jacobi
wavelet transform): Let L2 ( ) and ˆ ( )2 ( ) 0, 0
C d
then
for any f g L, 2( ) ; We get
(1) (2), 2 1, 2 1,
0 0 1
d k d k
C f g J f k k J g k k
k
(5.1)
To prove the above theorem, let us prove the following lemma:
Lemma 5.1: Let L2 ( ) be any basic wavelet then, ˆ , ( ) ˆ(1 ) (2)
2 1 k k
k k
From (3.6) we have
( ) ( ) , , ( )
, 1 2
2 1 x 0 k z k x z d z
k k
(2) ( ) ( ) (1 ) ( ) ( ) 0 0
k x z k z d z d
ˆ
(2) ( ) (1 ) ( ) 0
k x k d
ˆ (k1 ) (k2)
( )x3347
Therefore ˆ , ( ) ˆ(1 ) (2)
2 1
k k
k k
(5.2)
Proof: We have
( )(2 1, ) ( ) , ( ) ( ) 2 1 0
Jf k k f xk k x d x
( ), , ( ) 2 1
f xk k x
ˆ( ),ˆ , ( ) 2 1
f k k
ˆ( )ˆ ( ) ( ) ,
2 1 0
f k k d
ˆ( ) (ˆ 1 ) ( 2) ( ) 0
f k k d
ˆf( ) ( ˆ k1)
k2Similarly,
(J g k )(2 1,k)
gˆ( ) ( ˆk1)
k2Then
(1) ( 2) ( )( 2 1, )( )(2 1, )
0 0 1
d k d k
J f k k J g k k k
ˆ
(1) ( )ˆ ˆ ˆ
( ) (1 ) ( ) (1 )
0 0 1
d k d
f k g k
k
( ) ( )
2 1
ˆ
ˆ( ) (1 ) ˆ( )
0 0 1
d k d
g k g
k
2
ˆ (1 ) ˆ
ˆ (1) ( ) ( ) ( )
0 1 0
k
d k f g d
k
Let us take k1 , then we get 2
ˆ ( ) ( ) ˆ ˆ ( ) ( ) ( )
0 0
d
f g d
ˆ ( )2 ( ) ˆ( ) ( )ˆ ( )
0 0
d f g d
ˆ( ) ( )ˆ ( ) 0
C f g d
C f g,
Theorem 5.2 (Inversion formula): If f L2 ( ) , then
( ) ( )1 1 2
( ) 2 1, , ( )
2 1 1
d k d k
f x J f k k k k x
C k
(5.3)
Where ˆ ( )2 ( ) 0
C d
Proof: For any g L2 ( ) , we get
ˆ ˆ
, 2 ( ) ( ) ( )
0
C f gL C f x g x d x
(1) ( 2) ( )( 2 1, )( )( 2 1, )
0 0 1
d k d k
J f k k J g k k k
(1) (2) ( )(2 1, ) ( ) , ( ) ( )
2 1
0 0 0 1
d k d k
J f k k g x k k x d x
k
(1) (2)
( )(2 1, ) , ( ) ( ) ( )
2 1
0 0 0 1
d k d k
J f k k k k x g x d x
k
(1) (2)
( )(2 1, ) , ( ) ,
2 1
0 0 1
d k d k
J f k k k k x g x
k
Therefore
( ) ( )
1 1 2
( ) ( )(2 1, ) , ( ) 2 1
0 0 1
d k d k
f x J f k k k k x
C k
If fg, then
2
2 ,
2
2 0 0
dbda
f L J f b a
a
Moreover the Fourier- Jacobi wavelet transform is isometry
from L2 into L2 L2 .
6.
CALDERON’S FORMULA
In section 3, the wavelet , ( ) 2 1
x k k
defined by taking
translation operator first and then dilation operator. In this section to study the boundedness and continuity result we define the wavelet , ( )
1 2 x
k k
is defined by taking dilation
operator first and then translation operator. Moreover by using the wavelet , ( )
1 2 x
k k
and corresponding Fourier
Jacobi wavelet transform and Fourier Jacobi convolution we obtain Calderon’s reproducing identity and its applications.
Theorem 6.1: Let Lp( )
,
( ) 11 1 1
t t
k k k
for k1 0 and
2 ( )
f L then
( ) * * ( ) (1)
1 1
0 1
d k
f x k k f x
k
(6.1)
and we can convert the above expression in the following form
( )
,
2 (2) (1)2 1 2
0 0 1 1
x k d k d k
f x J f k k
k k
(6.2)
where
2 1,
2
( ) ( ) 10
Jf k k k x k f t dt
and
2 ( 2)
1 1
x k x k
k k
.
The Fourier-Jacobi wavelet is defined as follows:
Let us take Lp( ) be given, and for k20 and k10, we get
( ) ( ) ( , )
, 2
1 2 x D1 2 x D1 k x
k k k k k
1 2 ,
2, 11 1 1
k x
k x k
k k k
1 ( ) 2, , ( )
1 0 1 1
k x
z z d z
k k k
3348
Then the Fourier-Jacobi wavelet transform for the wavelet ( )
, 1 2
x k k
is defined as follows
J k k(1 2, )
Jf (k k1 2, ) ( ), , ( )1 2
f x k k x
( ) , ( ) ( ) 1 2 0
f xk k x d x
1 ( ) ( ) 2, , ( ) ( )
1 0 0 1 1
k x
f x z z d z d x
k k k
(6.4)
provided the integral is convergent.
Theorem 6.2: Let f L p( ) and Lq( ) with 1p q, and 1 1
1
p q , andJ(Jf)(k k1 2, ) be continuous wavelet
transform(6.4). Then
(1) J k k(1 2, ) is continuous on 0, 0,.
(2)
1, , , ,
1 2 ,
r
J f k k a f p q
r
1 1 1
1, 1 p q,
r p q
(3)
11
1 1
, , 1
1 2 , , ,
q
J f k k a f
p q p q
Proof:
(1) Let (2 ,1 ) 0 0
k k be an arbitrary but fixed point in
(0, ) (0, ) . Then by Hӧlder’s inequality.
(1 2, ) (1 ,2 ) 0 0
J k k J k k
2
1 2 0
( ) ( ) , , , , ( ) ( )
0 0 1 1 10 10
k
k x x
f x z z z d x d z
a k k k k
1
2
1 ( ) 2, , 0, , ( ) ( )
0 0 1 1 10 10
k p
k x x
p
f x z z d x d z
a k k k k
1
20 2
( ) , , , , ( ) ( )
0 0 1 1 10 10
k q
k x x
q
x z z d x d z
k k k k
Since
20
2 , , , , ( ) 2
0 1 1 10 10
k
k x x
z z d x
k k k k
, by dominated
convergence theorem and continuity of 2 , , 1 1
k x
z k k
in
the variable k2 and k1, we have
lim (1 2, ) (1 ,2 ) 0 0 0 2 20
1 10
J k k J k k
k k
k k
This proves that J k k(1 2, )is continuous on (0, ) (0, ) .
(2) From (7) the integral (3.2) is convergent for almost all x, 0 x and
h*r,hp,q,
(3) It can be proved using Hӧlder’s inequality.
Theorem 6.3: If f L1( )L2( ) , then f can be reconstructed by the formula
( ) 1 ( )( , ) 2, (1) (2)
1 2 2
0 0 1 1 1
k x d k d k
l x J l k k
C k k k
(6.5)
Where ˆ ( )2 ( ) 0
C d
and(Jf)(k2 1,k)is Fourier-Jacobi wavelet transform, we get
(1) (2) , ( )(1 2, )( )( 2 1, )
0 0 1
d k d k
C f g J f k k J g k k
k
(1) (2) ( )(1 2, ) ( ) , ( ) ( )
1 2
0 0 0 1
d k d k
J f k k g x k k x d x
k
( ) ( )
1 2 1 2
( )(1 2, ) ( ) , ( )
0 0 0 1 1 1 1
k x d k d k
J f k k g x d x
k k k k
( ) ( )
2 1 2
( )(1 2, ) , ( ) ( )
2
0 0 0 1 1 1
k x d k d k
J f k k g x d x
k k k
( ) ( )
2 1 2
( )(1 2, ) , , ( )
2
0 0 1 1 1
k x d k d k
J f k k g x
k k k
(6.6)
Therefore
( ) ( )
2 1 2
( ) ( )(1 2, ) ,
2
0 0 1 1 1
k x d k d k
C f x J f k k
k k k
(6.7)
If we take fg in equation (6.6) we get
2 ( )( , )2 (1) (2)
1 2 2
0 0 1
d k d k
C f J f k k
k
.
Lemma 6.1: Assume L2 ( ) be a basic Fourier-Jacobi wavelet that satisfies the admissibility condition
ˆ ( )2 ( ) 1 0
C d
. (6.8)
Then for f L1( )L2( )
( ) ( ) ( )
2 1 2 1
( )(1 2, ) , * * ( )
2 1 1
00 1 1 1 0 1
k x d k d k d k
J f k k f k k x
k k k k
(6.9)
Proof: From equation (6.4) we get ( ) ( )
2 1 2
( )(1 2, ) ,
2
0 0 1 1 1
k x d k d k
J f k k
k k k
* ( ) 2, (1) (2) 2 2
1
0 0 1 1 1
d k d k
k x
f k k
k k k
(6.10)
( ) ( )
2 1 2
( )(1 2, ) ,
2
0 0 1 1 1
k x d k d k
J f k k
k k k
(1) (2)* (2) ,2
1 1
0 0 1
d k d k
f k k k x k
k
3349 ( ) ( )
2 1 2
( )(1 2, ) ,
2
0 0 1 1 1
k x d k d k
J f k k
k k k
(1)
* * ( )
1 1
0 1
d k
f k k x
k
Theorem 6.2: Assume that h,L1( ) and (Jh J)()L1( ) holds the admissibility condition
( )( )( )( )ˆ ˆ ( ) 1 0
d h
.
Then the following Calderon’s reproducing identity holds (1) 1
( ) * * ( ) , ( )
1 1
0 1
d k
f x f k k x f L
k
.
Proof: If we put h in the above lemma, then we can find
the proof of this theorem.
7.
APPLICATIONS
Theorem 7.1: Assume L2 ( ) be a basic Fourier-Jacobi wavelet and
Jf
k k1 2,
be continuous Fourier-Jacobi wavelet transform, then( ) ( )
2 1 2
( )(1 2, ) ,
2
0 0 1 1 1
k x d k d k
J f k k
k k k
( ) ( ) 0
x
C Jf d
Proof: From equation (5.1), we get
( ) ( )
2 1 2
( )(1 2, ) ,
2
0 0 1 1 1
k x d k d k
J f k k
k k k
( ) ( )
2 1 2
( )(1 2, ) ( ) , , ( ) 2
0 0 0 1 1 1
k x d k d k
J f k k z k z d z
k k k
(1) (2) 2
( )(1 2, ) ( ) ( ) ( ) ( ) 2
0 0 0 0 1 1 1
d k d k
k x
J f k k z z d d z
k k k
( ) ( )
2 1 2
( )(1 2, ) ( ) ( ) ( ) ( )
2
0 0 0 1 1 0 1
k x d k d k
J f k k z z d z d
k k k
( ) ( )
2 1 2
( )(1 2, ) ( ) ( )
2
0 0 0 1 1 1
k x d k d k
J f k k J d
k k k
( ) 2 ( )( , ) ( ) (1) ( )
2 1 2 2
0 0 1 0 1 1
k d k d
x
J J f k k d k
k k k
( ) ( )( , ) (1) ( )
2 1 2
0 0 1 1 1
d k d
x
J J J f k k
k k k
Let us take 1
k , then we get
( ) ( )( , ) (1) ( )
1 2 1
0 0 1
d k d
x
J k J J f k k
k
( ) ( )( )( ) (1) ( )
1 1
0 0 1
d k d
x
J k J k J f
k
2 (1) ( )
(1 ) ( )
0 0 1
d k d
x
J k Jf
k
2 (1 )
( ) (1) ( )
0 0 1
J k
x
Jf d k d
k
( ) ( ) 0
x
C Jf d
.
8.
CONCLISION
In this paper we describe a new inversion and Plancherel formula for Fourier-Jacobi wavelet transform. Also we construct a Calderon’s reproducing formula for Fourier-Jacobi wavelet transform. Some applications associated with Calderon’s reproducing formula for Fourier-Jacobi convolution are also given.
REFERENCES
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[4] L. Debnath, Integral transforms and their applications, CRC Press, New York (199
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