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90 lines
3.0 KiB
Plaintext
90 lines
3.0 KiB
Plaintext
NAME
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crd - trigonometric chord of a unit circle
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SYNOPSIS
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crd(x [,eps])
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TYPES
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x number (real or complex)
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eps 0 < real < 1, defaults to epsilon()
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return number
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DESCRIPTION
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Calculate length of unit circle chord with angle x to a multiple of eps with error less in
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absolute value than .75 * eps.
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A chord of a circle is a straight line segment whose endpoints lie on a arc of a circle.
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A chord extended infinitely on both directions into a line would produce a secant line.
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This function is sometimes called chord, is equivalent to:
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crd(x) = 2 * sin(x / 2)
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EXAMPLE
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; print crd(1/2), crd(5/7), crd(42/7)
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0.4948079185090458592 0.6991976162706840944 0.2822400161197344442
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; print crd(1, 1e-5), crd(1, 1e-10), crd(1, 1e-15), crd(1, 1e-20)
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0.95886 0.9588510772 0.958851077208406 0.95885107720840600054
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; print crd(2 + 3i, 1e-5), crd(2 + 3i, 1e-10)
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3.95896+2.3009i 3.9589688712+2.3009091988i
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; pi = pi(1e-20)
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; print crd(pi/6), crd(pi/2), crd(pi)
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0.5176380902050415247 1.4142135623730950488 2
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LIMITS
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0 < eps < 1
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LINK LIBRARY
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NUMBER *qcrd(NUMBER *x, NUMBER *eps)
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COMPLEX *c_crd(COMPLEX *x, NUMBER *eps)
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SEE ALSO
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sin, cos, tan, cot, sec, csc
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asin, acos, atan, acot, asec, acsc
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coversin, vercos, covercos
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aversin, acoversin, avercos, acovercos
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haversin, hacoversin, havercos, hacovercos
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ahaversin, hacoversin, havercos, ahacovercos
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exsec, aexsec, excsc, aexcsc
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acrd
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cas, cis
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epsilon
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EXTERNAL RESOURCES
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For general information on trigonometric functions, see:
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https://en.wikipedia.org/wiki/Trigonometric_functions#Unit-circle_definitions
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https://en.wikipedia.org/wiki/Versine
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https://en.wikipedia.org/wiki/Exsecant
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https://en.wikipedia.org/wiki/Inverse_trigonometric_functions
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https://en.wikipedia.org/wiki/Chord_(geometry)
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https://en.wikipedia.org/wiki/Secant_line
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https://en.wikipedia.org/wiki/Hartley_transform#cas
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https://en.wikipedia.org/wiki/Cis_(mathematics)
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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: 2023/10/02 16:49:42
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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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