NAME
    acovercos - inverse coversed trigonometric cosine

SYNOPSIS
    acovercos(x [,eps])

TYPES
    x		number (real or complex)
    eps		0 < real < 1, defaults to epsilon()

    return	number

DESCRIPTION
    Calculate the inverse coversed trigonometric cosine of x to a multiple of eps with error less in
    absolute value than .75 * eps.

    This function is sometimes called acvc, or arccovercos, is equivalent to:

	acovercos(x) = asin(x - 1)

EXAMPLE
    ; print acovercos(0), acovercos(0.5), acovercos(1)
    1.57079632679489661923 0.52359877559829887308 0

    ; print acovercos(-0.5), acovercos(-1)
    -1.57079632679489661923+0.96242365011920689498i -1.57079632679489661923+1.31695789692481670863i

    ; print acovercos(.5, 1e-5), acovercos(.5, 1e-10), acovercos(.5, 1e-15), acovercos(.5, 1e-20)
    0.5236 0.5235987756 0.523598775598299 0.52359877559829887308

    ; print acovercos(5), acovercos(5i)
    1.57079632679489661923-2.06343706889556054673i -0.19379313655493218978+2.33097465304931241744i

    ; print acovercos(5+5i)
    0.66881657532592728975+2.5513216254756988588i

    ; pi = pi(1e-20)
    ; print acovercos(pi/6), acovercos(pi/3), acovercos(4*pi/3)
    0.49655704344777825545 -0.04721509173238348552 1.57079632679489661923-1.82724307729474887791i

LIMITS
    0 < eps < 1

LINK LIBRARY
    NUMBER *qacovercos(NUMBER *x, NUMBER *eps)
    COMPLEX *c_acovercos(COMPLEX *x, NUMBER *eps)

SEE ALSO
    sin, cos, tan, cot, sec, csc
    asin, acos, atan, acot, asec, acsc
    versin, coversin, vercos, covercos
    aversin, acoversin, avercos
    haversin, hacoversin, havercos, hacovercos
    ahaversin, hacoversin, havercos, ahacovercos
    epsilon

## Copyright (C) 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:	2023/09/05 23:30:08
## File existed as early as:	2023
##
## chongo <was here> /\oo/\	http://www.isthe.com/chongo/
## Share and enjoy!  :-)	http://www.isthe.com/chongo/tech/comp/calc/