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Evaluation of \(\int_0^{2\pi}\exp(iax+b\cos mx+c\cos nx)\,dx\) and \(\int_0^{2\pi}\exp(iax+b\sin mx+c\cos nx)\,dx\) for \(a,m,n\in\mathbb Z\) and \(b,c\in\mathbb C\) in terms of modified Bessel function of the first kind. (English) Zbl 1142.33001

The authors work out and define integrals involving modified Bessel function of first kind \(I_\nu(x)\). The integral is \[ \int^{2\pi}_0 \exp[iax+ b\cos mx+ c\cos nx]\,dx \] \(\forall a,m,n\in\mathbb{Z}\) and \(b,c\in \mathbb{C}\). Particular cases provide results derived earlier.

MSC:

33C10 Bessel and Airy functions, cylinder functions, \({}_0F_1\)
33C65 Appell, Horn and Lauricella functions
33C45 Orthogonal polynomials and functions of hypergeometric type (Jacobi, Laguerre, Hermite, Askey scheme, etc.)