Some Curious Results Involving Certain Polynomials
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Available online a t www.scholarsresearchlibrary.com Scholars Research Library European Journal of Applied Engineering and Scientific Research, 2014, 3 (1):21-30 (http://scholarsresearchlibrary.com/archive.html) ISSN: 2278 – 0041 Some curious results involving certain polynomials Salahuddin and R.K. Khola Mewar University, Gangrar, Chittorgarh (Rajasthan) , India _____________________________________________________________________________________________ ABSTRACT In this paper we have developed some curious results involving certain polynomials. Key Words : Hypergeometric function, Laplace Transform, Lucas Polynomials, Gegenbaur polynomials, Harmonic number, Bernoulli Polynomial, Hermite Polynomials. 2010 MSC NO : 11B39, 11B68, 33C05, 33C45, 33D50, 33D60 _____________________________________________________________________________________________ INTRODUCTION We have the generalized Gaussian hypergeometric function of one variable ∞ ….. AFB(a 1,a 2,…,a A;b 1,b 2,…b B;z ) =∑ (1.1) ….. ! where the parameters b1 , b 2 , ….,b B are neither zero nor negative integers and A , B are non negative integers. The series converges for all finite z if A ≤ B, converges for │z│<1 if A=B +1, diverges for all z, z ≠ 0 if A > B+1. Laplace Transform The Laplace Transform of a function f(t) , defined for all real numbers t ≥0, is the function F(s), defined by : ∞ − Fs()= Lft {()}() s = ∫ est ftdt () 0 (1.2) The parameter s is a complex number: s=σ + i ω , with real number σ and ω . Jacobi Polynomials In mathematics, Jacobi polynomials (occasionally called hypergeometric polynomials ) are a class of classical orthogonal polynomials. They are orthogonal with respect to the weight α β (1−x ) (1 + x ) on the interval [-1, 1]. The Gegenbauer polynomials, and thus also the Legendre, Zernike and Chebyshev polynomials, are special cases of the Jacobi polynomials. The Jacobi polynomials were introduced by Carl Gustav Jacob Jacobi. The Jacobi polynomials are defined via the hypergeometric function as follows: 21 Scholars Research Library Salahuddin and R.K. Khola Euro. J. Appl. Eng. Sci. Res., 201 4, 3 (1):21-30 _____________________________________________________________________________ α β (α + 1) − ( , ) =n −++++α β α 1 z Pzn ()2 Fn 1 (,1 n ;1; ), n! 2 (1.3) α + Where ( 1) n is Pochhammer’s symbol. In this case, the series for the hypergeometric function is finite, therefore one obtains the following equivalent expression: Γ++αn Γ++++− α β (α , β ) = (n 1) n ! ( nmz 1) 1 m Pn ( z ) ∑ ( ) n!(Γ+++α β n 1)= mnm !() − ! Γ++ ( α m 1) 2 m 0 (1.4) Lucas Polynomials The Lucas polynomials are the w-polynomials obtained by setting p(x) = x and q(x) = 1 in the Lucas polyno mials sequence. It is given explicitly by =−n −2 + n +2 + n Lxn ()2[( xx 4 ) + (x x 4 ) ] (1.5 ) The first few are = L1( x ) x L( x )= x 2 + 2 2 (1.6) =3 + Lx3 ( ) x 3 x =4 + 2 + Lx4 () x 4 x 2 Generalized Harmonic Number The generalized harmonic number of order n of m is given by n (m ) = 1 H n ∑ m k=1 k (1.7) In the limit of n → ∞ the generalized harmonic number converges to the Riemann zeta function (m ) = ς limHn ( m ) n→∞ (1.8) 22 Scholars Research Library Salahuddin and R.K. Khola Euro. J. Appl. Eng. Sci. Res., 2014, 3 (1):21-30 _____________________________________________________________________________ Bernoulli Polynomial In mathematics, the Bernoulli polynomials occur in the study of many special functions and in particular the Riemann zeta function and Hurwitz zeta function. This is in large part because they are an Appell sequence, i.e. a Sheffer sequence for the ordinary derivative operator. Unlike orthogonal polynomials, the Bernoulli polynomials are remarkable in that the number of crossing of the x-axis in the unit interval does not go up as the degree of the polynomials goes up. In the limit of large degree, the Bernoulli polynomials, appropriately scaled, approach the sine and cosine functions. Explicit formula of Bernoulli polynomials is n n! Bx( ) = bx k , for n 0, where b are the Bernoulli numbers. n∑ − n− k ≥ k k =0 k!() n k ! The generating function for the Bernoulli polynomials is text∞ t n = B( x ) t − ∑ n e1n=0 n ! (1.9) Gegenbauer polynomials (ɑ) In Mathematics, Gegenbauer polynomials or ultraspherical polynomials C n (x) are orthogonal polynomials on the α −1 interval [-1,1] with respect to the weight function (1− x2 ) 2 . They generalize Legendre polynomials and Chebyshev polynomials, and are special cases of Jacobi polynomials. They are named after Leopold Gegenbauer . Explicitly , n 2 α Γ(n − k + α ) − C() () x= (1) − k (2) z ( n 2 k ) n ∑ Γα − k =0 ( )!(k n 2)! k (1.10) 23 Scholars Research Library Salahuddin and R.K. Khola Euro. J. Appl. Eng. Sci. Res., 2014, 3 (1):21-30 _____________________________________________________________________________ Laguerre polynomials The Laguerre polynomials are solutions Ln ( x ) to the Laguerre differential equation xy''+− (1 x ) y ' +λ y = 0 , which is a special case of the more general associated Laguerre differential equation, defined by xy''(++−ν 1 xy )' + λ y = 0 , where λ and ν are real numbers with ν =0. The Laguerre polynomials are given by the sum n − k = ( 1)n ! k Ln ( x ) ∑ x = k! kn !()− k ! k 0 (1.11) Hermite polynomials The Hermite polynomials Hn ( x ) are set of orthogonal polynomials over the domain (-∞,∞) with weighting − 2 function e x . The Hermite polynomials Hn ( x ) can be defined by the contour integral = n! −+r2 2 rz −− n 1 Hzn ( ) ∫ e tdt , 2πi Where the contour incloses the origin and is traversed in a counterclockwise direction 24 Scholars Research Library Salahuddin and R.K. Khola Euro. J. Appl. Eng. Sci. Res., 201 4, 3 (1):21-30 _____________________________________________________________________________ (Arfken 1985, p. 416). The first few Hermite polynomials are = H0 ( x ) 1 = H1( x ) 2 x H() x= 4 x 2 − 2 2 (1.12) =3 − Hx3 () 8 x 12 x =4 − 2 + Hx4 () 16 x 48 x 12 Legendre function of the first kind The Legendre po lynomials, sometimes called Legendre functions of the first kind, Legendre coefficients, or zonal harmonics (Whittaker and Watson 1990, p. 302), are solutions to the Legendre differential equation . If l is an integer, they are polynomials . The Legendre polyn omials Pn ( x ) are illustrated above for and n=1, 2, ..., 5. The Legendre polynomials Pn ( x ) can be defined by the contour integral −1 1 − − = − + 22 n 1 Pzn ( )∫ (1 2 tzt ) tdt , (1.13) 2πi where the contour encloses the origin and i s traversed in a counterclockwise direction (Arfken 1985, p. 416). Legendre function of the second kind 25 Scholars Research Library Salahuddin and R.K. Khola Euro. J. Appl. Eng. Sci. Res., 201 4, 3 (1):21-30 _____________________________________________________________________________ The second solution to the Legendre differential equation . The Leg endre functions of the second kind satisfy the same recurrence relation as the Legendre polynomials . The first few are 1 1+ x Q( x ) = ln( ) 0 2 1− x x 1+ x Q( x ) = ln( )-1 (1 .14) 1 2 1− x 3x2 − 1 1+ x 3x Q( x ) = ln( )- 2 4 1− x 2 Chebyshev polynomial of the first kind The Chebyshev polynomials of the first kind are a set of orthogonal polynomials defined as the solutions to the Chebyshev differential equation and denoted Tn ( x ) . They are used as an approximation to a least squares fit, and are a special case of the Gegenbauer polynomial with . They are also intimately connected with trigonometric multiple-angle formulas . The Chebyshev polynomial of the first kind Tn ( z ) can be defined by the contour integral 1 (1−t2 ) t −n − 1 = , (1.15) Tn ( z ) ∫ 2 dt 4πi 1− 2 tzt + where the contour encloses the origin and is traversed in a counterclockwise direction (Arfken 1985, p. 416). The first few Chebyshev polynomials of the first kind are = T0 ( x ) 1 = T1( x ) x =2 − T2 () x 2 x 1 =3 − Tx3 () 4 x 3 x A beautiful plot can be obtained by plotting Tn ( x ) radially, increasing the radius for each value of n , and filling in the areas between the curves (Trott 1999, pp. 10 and 84). 26 Scholars Research Library Salahuddin and R.K. Khola Euro. J. Appl. Eng. Sci. Res., 201 4, 3 (1):21-30 _____________________________________________________________________________ The Chebyshev polynomials of the first kind are defined through the identity Tn(cos θ)=cos nθ. Chebyshev polynomial of the second kind A modified set of Chebyshev polynomials defined by a slightly different generating function . They arise in the development of four-dimensional spherical harmonics in angular momentum theory. They are a special case of the Gegenbauer polynomial with . They are also intimately connected with trigonometric multiple-angle formulas. The first few Cheby shev polynomials of the second kind are = U0 ( x ) 1 U( x )= 2 x 1 (1.16) =2 − U2 () x 4 x 1 =3 − Ux3 () 8 x 4 x 27 Scholars Research Library Salahuddin and R.K. Khola Euro. J. Appl. Eng. Sci. Res., 2014, 3 (1):21-30 _____________________________________________________________________________ Euler polynomial The Euler polynomial En ( x ) is given by the Appell sequence with 1 g( t )= ( e t + 1) , 2 giving the generating function 2ext∞ t n ≡ E( x ) . (1.17) t + ∑ n e1n=0 n ! The first few Euler polynomials are = E0 ( x ) 1 1 E( x ) = x − 1 2 Ex( ) = x2 − x 2 (1.18) 3 1 Ex( ) = x3 − x 2 + 3 2 4 1. MAIN RESULTS − 2 1− 2n 2 −−n− − n + xnF(2 1 ( ,;; x ) 4 x 1 − L( x ) 1 + x n dx = 2 n n + C ∫ 1 − 2(n 4) (2.1) − 1− 1n 1 −−n− − n + nx2 F 1 (,;; x ) 2 x x 1 − H(x ) 1+ x n dx = 2 n n + C ∫ 1 − (n 2) (2.2) − + −n 1 −1 − 2n 2 − −n ∫ B1( x ) 1 x dx = x[ (2)nnxF2 1 ( ,; ; x ) 2(n− 4)( n − 2) 2 n n 28 Scholars Research Library Salahuddin and R.K.