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calc/help/prevprime
Landon Curt Noll a31078bbec Remove all RCS @(#) lines and RCS strings
Some folks might think: “you still use RCS”?!?  And we will say,
hey, at least we switched from SCCS to RCS back in … I think it was
around 1994 ... at least we are keeping up! :-) :-) :-)

Logs say that SCCS version 18 became RCS version 19 on 1994 March 18.

RCS served us well.  But now it is time to move on.   And so we are
switching to git.

Calc releases produce a lot of file changes.  In the 125 releases
of calc since 1996, when I started managing calc releases, there
have been 15473 file mods!
2017-05-23 01:33:23 -07:00

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NAME
prevprime - nearest prime less than specified number
SYNOPSIS
prevprime(n [,err])
TYPES
n real
err integer
return positive integer or err
DESCRIPTION
If n is an integer and 2 < n < 2^32, prevprime(n) returns the
nearest prime less than n.
If n <= 2 or >= 2^32 or n is fractional, prevprime(n, err)
returns the value of err.
Other cases cause a runtime error.
EXAMPLE
; print prevprime(10), prevprime(100), prevprime(1e6)
7 97 999983
; print prevprime(2,-99), prevprime(2^32,-99)
-99 -99
; print prevprime(2)
pprime arg 1 is <= 2
LIMITS
2 < n < 2^32
LINK LIBRARY
FULL zpprime(ZVALUE z)
SEE ALSO
factor, isprime, lfactor, nextcand, nextprime, prevcand,
pfact, pix, ptest
## Copyright (C) 1999-2006 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: 1995/12/18 12:34:58
## File existed as early as: 1995
##
## chongo <was here> /\oo/\ http://www.isthe.com/chongo/
## Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/