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NAME
sech - hyperbolic secant
SYNOPSIS
sech(x [,eps])
TYPES
x real
eps 0 < real < 1, defaults to epsilon()
return real
DESCRIPTION
Calculate the sech of x to the nearest or next to nearest multiple of
epsilon, with absolute error less than .75 * abs(eps).
sech(x) = 2/(exp(x) + exp(-x))
EXAMPLE
; print sech(1, 1e-5), sech(1, 1e-10), sech(1, 1e-15), sech(1, 1e-20)
0.64805 0.6480542737 0.648054273663885 0.64805427366388539958
LIMITS
unlike sin and cos, x must be real
0 < eps < 1
LINK LIBRARY
NUMBER *qsech(NUMBER *x, NUMBER *eps)
SEE ALSO
sinh, cosh, tanh, coth, csch
asinh, acosh, atanh, acoth, asech, acsch
epsilon
## Copyright (C) 1999,2021,2023 Landon Curt Noll
##
## Calc is open software; you can redistribute it and/or modify it under
## the terms of the version 2.1 of the GNU Lesser General Public License
## as published by the Free Software Foundation.
##
## Calc is distributed in the hope that it will be useful, but WITHOUT
## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
## or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
## Public License for more details.
##
## A copy of version 2.1 of the GNU Lesser General Public License is
## distributed with calc under the filename COPYING-LGPL. You should have
## received a copy with calc; if not, write to Free Software Foundation, Inc.
## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
##
## Under source code control: 1995/11/13 03:49:00
## File existed as early as: 1995
##
## chongo <was here> /\oo/\ http://www.isthe.com/chongo/
## Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/
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