BESSELITILDE I-type Bessel function after factoring off exponential growth. ITILDE=BESSELITILDE(NU,Z) returns the modified Bessel function of the first kind of order NU at argument Z, after factoring off the asymptotic behavior of EXP(Z). BESSELITILDE is useful for products of modified Bessel functions in which the exponential behaviors cancel, but that cannot be evaluated directly because of numerical overflow. BESSELITILDE(NU,Z,N) use a summation truncated at N terms. The default behavior uses N=30 and is highly accurate. See 10.40.1 of https://dlmf.nist.gov/10.40. This is low-level code used by WINDTRANS using an algorithm described in Lilly and Elipot (2021). See also BESSELKTILDE. 'besselitilde --t' runs a test. Usage: I=besselitilde(nu,z); I=besselitilde(nu,z,nterms); __________________________________________________________________ This is part of JLAB --- type 'help jlab' for more information (C) 2019--2021 J.M. Lilly --- type 'help jlab_license' for details