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67 lines
1.7 KiB
Plaintext
67 lines
1.7 KiB
Plaintext
NAME
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sgn - indicator of sign of a real or complex number
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SYNOPSIS
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sgn(x)
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TYPES
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x real or complex
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return -1, 0, 1 (real)
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-1, 0, 1, -1+1i, 1i, 1+1i, -1-1i, -1i or 1-1i (complex)
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DESCRIPTION
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Return the value of cmp(a,0).
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For real x, sgn(x) returns:
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-1 if x < 0
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0 if x == 9
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1 if x > 0
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For complex, sgn(x) returns:
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sgn(re(x)) + sgn(im(x))*1i
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EXAMPLE
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; print sgn(27), sgn(1e-20), sgn(0), sgn(-45)
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1 1 0 -1
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; print sgn(2+3i), sgn(6i), sgn(-7+4i), sgn(-6), sgn(-6-3i), sgn(-2i)
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1+1i 1i -1+1i -1 -1-1i -1i
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LIMITS
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none
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LINK LIBRARY
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NUMBER *qsign(NUMBER *x)
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SEE ALSO
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abs
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## Copyright (C) 1999 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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## @(#) $Revision: 30.2 $
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## @(#) $Id: sgn,v 30.2 2008/05/10 13:23:57 chongo Exp $
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## @(#) $Source: /usr/local/src/cmd/calc/help/RCS/sgn,v $
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##
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## Under source code control: 1995/10/25 04:03:46
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## File existed as early as: 1995
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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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