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Diffstat (limited to 'math/slalib/random.F__vms')
-rw-r--r-- | math/slalib/random.F__vms | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/math/slalib/random.F__vms b/math/slalib/random.F__vms new file mode 100644 index 00000000..b57b5fc9 --- /dev/null +++ b/math/slalib/random.F__vms @@ -0,0 +1,69 @@ + REAL FUNCTION sla_RANDOM (SEED) +*+ +* - - - - - - - +* R A N D O M +* - - - - - - - +* +* Generate pseudo-random real number in the range 0 <= X < 1. +* (single precision) +* +* !!! Version for VAX/VMS and DECstation !!! +* +* Given: +* SEED real an arbitrary real number +* +* Notes: +* +* 1) The result is a pseudo-random REAL number in the range +* 0 <= sla_RANDOM < 1. +* +* 2) SEED is used first time through only. +* +* Called: RAN (a REAL function from the DEC Fortran Library) +* +* P.T.Wallace Starlink 14 October 1991 +* +* License: +* This program is free software; you can redistribute it and/or modify +* it under the terms of the GNU General Public License as published by +* the Free Software Foundation; either version 2 of the License, or +* (at your option) any later version. +* +* This program 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 General Public License for more details. +* +* You should have received a copy of the GNU General Public License +* along with this program (see SLA_CONDITIONS); if not, write to the +* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, +* Boston, MA 02110-1301 USA +* +*- + + IMPLICIT NONE + + REAL SEED + + REAL RAN + + REAL AS + INTEGER ISEED + LOGICAL FIRST + SAVE FIRST + DATA FIRST /.TRUE./ + + + +* If first time, turn SEED into a large, odd integer + IF (FIRST) THEN + AS=ABS(SEED)+1.0 + ISEED=NINT(AS/10.0**(NINT(ALOG10(AS))-6)) + IF (MOD(ISEED,2).EQ.0) ISEED=ISEED+1 + FIRST=.FALSE. + END IF + +* Next pseudo-random number + sla_RANDOM=RAN(ISEED) + + END |