On nonoscillating integrals for computing inhomogeneous Airy functions

Integral representations are considered of solutions of the inhomogeneous Airy differential equation $w''-z,w=pm1/pi$. The solutions of these equations are also known as Scorer functions. Certain functional relations for these functions are used to confine the discussion to one function and to a certain sector in the complex plane. By using steepest descent methods from asymptotics, the standard integral representations of the Scorer functions are modified in order to obtain non-oscillating integrals for complex values of $z$. In this way stable representations for numerical evaluations of the functions are obtained. The methods are illustrated with numerical results.

[1]  Nico Temme,et al.  Steepest descent paths for integrals defining the modified Bessel functions of imaginary order , 1993 .

[2]  Roy G. Gordon,et al.  An algorithm for the evaluation of the complex Airy functions , 1979 .

[3]  Roderick Wong,et al.  Asymptotic approximations of integrals , 1989, Classics in applied mathematics.

[4]  Irene A. Stegun,et al.  Handbook of Mathematical Functions. , 1966 .

[5]  Soo-Y. Lee,et al.  The inhomogeneous Airy functions, Gi(z) and Hi(z) , 1980 .

[6]  Milton Abramowitz,et al.  Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables , 1964 .

[7]  R. S. Scorer,et al.  NUMERICAL EVALUATION OF INTEGRALS OF THE FORM I=∫x1x2f(x)eiϕ(x)dx AND THE TABULATION OF THE FUNCTION Gi(z)=(1/π)∫0∞sin(uz+13u3) du , 1950 .

[8]  D. E. Amos Algorithm 644: A portable package for Bessel functions of a complex argument and nonnegative order , 1986, TOMS.

[9]  Walter Gautschi,et al.  NUMERICAL EVALUATION OF SPECIAL FUNCTIONS , 2001 .

[10]  Allan J. MacLeod,et al.  Computation of inhomogeneous Airy functions , 1994 .

[11]  Robert M. Corless,et al.  Numerical evaluation of airy functions with complex arguments , 1992 .

[12]  N. Temme Special Functions: An Introduction to the Classical Functions of Mathematical Physics , 1996 .

[13]  D. E. Amos,et al.  A remark on Algorithm 644: “A portable package for Bessel functions of a complex argument and nonnegative order” , 1995, TOMS.

[14]  Ronald F. Boisvert,et al.  Guide to Available Mathematical Software. , 1984 .

[15]  F. Olver Asymptotics and Special Functions , 1974 .