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4e5fcc8812
Added log2(x [,eps]) builtin function. When x is an integer power of 2, log2(x) will return an integer, otherwise it will return the equivalent of ln(x)/ln(2).
74 lines
2.4 KiB
Plaintext
74 lines
2.4 KiB
Plaintext
NAME
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log2 - base 10 logarithm
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SYNOPSIS
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log2(x [,eps])
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TYPES
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x nonzero real or complex
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eps nonzero real, defaults to epsilon()
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return real or complex
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DESCRIPTION
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Approximate the base 2 logarithm function of x by a multiple of
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epsilon, the error having absolute value less than 0.75 * eps.
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When x is an integer power of 2, log2(x) will return an integer
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regardless of the value of eps or epsilon().
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If y is a positive integer, log(x, 2^-y) will usually be correct
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to the y-th decimal place.
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EXAMPLE
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; print log2(2), log2(4), log2(1024), log2(2^500), log2(1/2^23209)
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1 2 10 500 -23209
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; print log2(127), log2(23209), log2(2^17-19)
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6.98868468677216585326 14.50239674255407864468 16.99979085393743521984
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; print log2(-127)
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6.98868468677216585326+4.53236014182719380961i
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; print log2(2+3i), log2(-2+3i)
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1.85021985907054608020+1.41787163074572199658i 1.85021985907054608020+3.11448851108147181304i
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; print log2(2-3i), log2(-2-3i)
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1.85021985907054608020-1.41787163074572199658i 1.85021985907054608020-3.11448851108147181304i
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; print log2(17+0.3i, 1e-75), log2(-17-0.3i, 1e-75)
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4.08768744737521449955+0.02545668190826163773i 4.08768744737521449955-4.50690345991893217190i
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LIMITS
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x != 0
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eps > 0
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LINK LIBRARY
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NUMBER *qlog2(NUMBER *x, NUMBER *eps)
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COMPLEX *c_log2(COMPLEX *x, NUMBER *eps)
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SEE ALSO
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ilog, ilogn, ilog10, ilog2, ln, log, logn
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## Copyright (C) 2023 Landon Curt Noll
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##
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## Calc is open software; you can redistribute it and/or modify it under
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## the terms of the version 2.1 of the GNU Lesser General Public License
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## as published by the Free Software Foundation.
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##
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## Calc is distributed in the hope that it will be useful, but WITHOUT
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## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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## or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
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## Public License for more details.
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##
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## A copy of version 2.1 of the GNU Lesser General Public License is
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## distributed with calc under the filename COPYING-LGPL. You should have
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## received a copy with calc; if not, write to Free Software Foundation, Inc.
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## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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##
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## Under source code control: 2023/08/19 09:14:04
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## File existed as early as: 2023
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##
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## chongo <was here> /\oo/\ http://www.isthe.com/chongo/
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## Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/
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