BIS1 3CW "22 April 2008" "mathcw-1.00"

Table of contents


NAME

bis1f, bis1, bis1l, bis1w, bis1q, bis1ll, bis1df, bis1d, bis1dl, bis1dll - exponentially-scaled modified Bessel function of first kind and order 1

SYNOPSIS

cc [ flags ] -I/usr/local/include file(s) -L/usr/local/lib -lmcw [ ... ]

#include <mathcw.h>

extern float bis1f (float x);

extern double bis1 (double x);

extern long double bis1l (long double x);

extern __float80 bis1w (__float80 x);

extern __float128 bis1q (__float128 x);

extern long_long_double bis1ll (long_long_double x);

extern decimal_float bis1df (decimal_float x);

extern decimal_double bis1d (decimal_double x);

extern decimal_long_double bis1dl (decimal_long_double x);

extern decimal_long_long_double bis1dll (decimal_long_long_double x);

NB: Functions with prototypes containing underscores in type names may be available only with certain extended compilers.


DESCRIPTION

Compute the exponentially-scaled modified Bessel function of the first kind and order 1, Is(1,x), mathematically equivalent to exp(-x) I(1,x), although not computed that way.

The modified Bessel functions provided by these software implementations are defined according to Chapter 9, Bessel Functions of Integer Order, of the Handbook of Mathematical Functions, edited by Milton Abramowitz and Irene A. Stegun, National Bureau of Standards Applied Mathematics Series #55, US Department of Commerce, Washington, DC (1964).


CAVEAT

Although in mathematics, uppercase letters name the ordinary and modified Bessel functions, and lowercase letters name the spherical Bessel functions, the lowercase names of the POSIX Bessel functions mean the former, not the latter.

RETURN VALUES

If the argument is finite, its modified Bessel function value of the first kind and order 1 is returned. Otherwise, a quiet NaN is returned.

ERRORS

If the argument is a NaN, errno is set to EDOM, and that NaN is returned.

SEE ALSO

bi0(3CW), bi1(3CW), bin(3CW), bis0(3CW), bisn(3CW), bk0(3CW), bk1(3CW), bkn(3CW), bks0(3CW), bks1(3CW), bksn(3CW), j0(3CW), j1(3CW), jn(3CW), sbi0(3CW), sbi1(3CW), sbin(3CW), sbis0(3CW), sbis1(3CW), sbisn(3CW), sbj0(3CW), sbj1(3CW), sbjn(3CW), sbk0(3CW), sbk1(3CW), sbkn(3CW), sbks0(3CW), sbks1(3CW), sbksn(3CW), sby0(3CW), sby1(3CW), sbyn(3CW), vbi(3CW), vbis(3CW), vbj(3CW), vbk(3CW), vbks(3CW), vby(3CW), vsbi(3CW), vsbis(3CW), vsbj(3CW), vsbk(3CW), vsbks(3CW), vsby(3CW), y0(3CW), y1(3CW), yn(3CW).