.\" Copyright (c) 1985, 1991 Regents of the University of California.
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.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
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.\"     from: @(#)j0.3	6.7 (Berkeley) 4/19/91
.\"	$NetBSD: j0.3,v 1.16 2003/08/07 16:44:48 agc Exp $
.\"
.Dd April 19, 1991
.Dt J0 3
.Os
.Sh NAME
.Nm j0 ,
.Nm j0f ,
.Nm j1 ,
.Nm j1f ,
.Nm jn ,
.Nm jnf ,
.Nm y0 ,
.Nm y0f ,
.Nm y1 ,
.Nm y1f ,
.Nm yn ,
.Nm ynf
.Nd Bessel functions of first and second kind
.Sh LIBRARY
.Lb libm
.Sh SYNOPSIS
.In math.h
.Ft double
.Fn j0 "double x"
.Ft float
.Fn j0f "float x"
.Ft double
.Fn j1 "double x"
.Ft float
.Fn j1f "float x"
.Ft double
.Fn jn "int n" "double x"
.Ft float
.Fn jnf "int n" "float x"
.Ft double
.Fn y0 "double x"
.Ft float
.Fn y0f "float x"
.Ft double
.Fn y1 "double x"
.Ft float
.Fn y1f "float x"
.Ft double
.Fn yn "int n" "double x"
.Ft float
.Fn ynf "int n" "float x"
.Sh DESCRIPTION
The functions
.Fn j0 ,
.Fn j0f ,
.Fn j1
and
.Fn j1f
compute the
.Em Bessel function of the first kind of the order
0 and the
.Em order
1, respectively,
for the
real value
.Fa x ;
the functions
.Fn jn
and
.Fn jnf
compute the
.Em Bessel function of the first kind of the integer order
.Fa n
for the real value
.Fa x .
.Pp
The functions
.Fn y0 ,
.Fn y0f ,
.Fn y1
and
.Fn y1f
compute the linearly independent
.Em Bessel function of the second kind of the order
0 and the
.Em order
1, respectively,
for the
positive
.Em integer
value
.Fa x
(expressed as a double);
the functions
.Fn yn
and
.Fn ynf
compute the
.Em Bessel function of the second kind for the integer order
.Fa n
for the positive
.Em integer
value
.Fa x
(expressed as a double).
.Sh RETURN VALUES
If these functions are successful,
the computed value is returned, otherwise
the global
variable
.Va errno
is set to
.Er EDOM
and a reserve operand fault is generated.
.\" On the
.\" .Tn VAX
.\" and
.\" .Tn Tahoe
.\" architectures, a negative
.\" .Fa x
.\" value
.\" results in an error.
.Sh SEE ALSO
.Xr math 3
.\" .Xr matherr 3
.Sh HISTORY
This set of functions
appeared in
.At v7 .