NAME
    log2 -  base 10 logarithm

SYNOPSIS
    log2(x [,eps])

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

    return      real or complex

DESCRIPTION
    Approximate the base 2 logarithm function of x by a multiple of
    epsilon, the error having absolute value less than 0.75 * eps.

    When x is an integer power of 2, log2(x) will return an integer
    regardless of the value of eps or epsilon().

    If y is a positive integer, log2(x, 2^-y) will usually be correct
    to the y-th decimal place.

EXAMPLE
    ; print log2(2), log2(4), log2(1024), log2(2^500), log2(1/2^23209)
    1 2 10 500 -23209

    ; print log2(127), log2(23209), log2(2^17-19)
    6.98868468677216585326 14.50239674255407864468 16.99979085393743521984

    ; print log2(-127)
    6.98868468677216585326+4.53236014182719380961i

    ; print log2(2+3i), log2(-2+3i)
    1.85021985907054608020+1.41787163074572199658i 1.85021985907054608020+3.11448851108147181304i

    ; print log2(2-3i), log2(-2-3i)
    1.85021985907054608020-1.41787163074572199658i 1.85021985907054608020-3.11448851108147181304i

    ; print log2(17+0.3i, 1e-75), log2(-17-0.3i, 1e-75)
    4.08768744737521449955+0.02545668190826163773i 4.08768744737521449955-4.50690345991893217190i

LIMITS
    x != 0
    0 < eps < 1

LINK LIBRARY
    NUMBER *qlog2(NUMBER *x, NUMBER *eps)
    COMPLEX *c_log2(COMPLEX *x, NUMBER *eps)

SEE ALSO
    ilog, ilogn, ilog10, ilog2, ln, log, logn

## 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.
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## Calc is distributed in the hope that it will be useful, but WITHOUT
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## 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
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## 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
##
## Under source code control:   2023/08/19 09:14:04
## 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/
