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psblas3/base/serial/aux/ibsrch.f

57 lines
2.1 KiB
Fortran

C
C Parallel Sparse BLAS v2.0
C (C) Copyright 2006 Salvatore Filippone University of Rome Tor Vergata
C Alfredo Buttari University of Rome Tor Vergata
C
C Redistribution and use in source and binary forms, with or without
C modification, are permitted provided that the following conditions
C are met:
C 1. Redistributions of source code must retain the above copyright
C notice, this list of conditions and the following disclaimer.
C 2. Redistributions in binary form must reproduce the above copyright
C notice, this list of conditions, and the following disclaimer in the
C documentation and/or other materials provided with the distribution.
C 3. The name of the PSBLAS group or the names of its contributors may
C not be used to endorse or promote products derived from this
C software without specific written permission.
C
C THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
C ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
C TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
C PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PSBLAS GROUP OR ITS CONTRIBUTORS
C BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
C CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
C SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
C INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
C CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
C ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
C POSSIBILITY OF SUCH DAMAGE.
C
C
subroutine ibsrch(ipos,key,n,v)
implicit none
integer ipos, key, n
integer v(n)
integer lb, ub, m
lb = 1
ub = n
ipos = -1
do while (lb.le.ub)
m = (lb+ub)/2
if (key.eq.v(m)) then
ipos = m
lb = ub + 1
else if (key.lt.v(m)) then
ub = m-1
else
lb = m + 1
end if
enddo
return
end