+- HP Forums (https://www.hpmuseum.org/forum)
+-- Forum: HP Software Libraries (/forum-10.html)
+--- Forum: General Software Library (/forum-13.html)
+--- Thread: (48G) 48G, 49G & 50G: Explicit Inverse Congruential Random Number Generator (/thread-4409.html)
(48G) 48G, 49G & 50G: Explicit Inverse Congruential Random Number Generator - Gerald H - 07-23-2015 07:21 AM
An Explicit Inverse Coungruential Random Number Generator to base 2 ^WORDSIZE.
SDR seeds constants a & b with suitable values to ensure maximum period & the counter j with a random value.
NEXTX produces the next hexadecimal string in the sequence using the formula
next := j * ( j * a + b ) ^ -1 MODULO 2 ^ WORDSIZE
where j increases by 1 at each iteration.
NEXTR returns the next real in the sequence, next divided by the modulus.
TO USE:
Set wordsize as required, actuate SDR - NEXTX or NEXTR will then return the sequence you require.
I would be grateful for reports of (in-)adequacy of the randomness of sequences produced.
Code:
SDR
::
CK0
BINT3
ZERO_DO
BINT2
ZERO_DO
%RAN
% 1.E12
%*
%>#
LOOP
bit*
LOOP
'
ID j
STO
HXS 00001 4
DUPUNROT
bit/
bit*
HXS 00001 2
bit+
'
ID a
STO
HXS 00001 2
DUPUNROT
bit/
bit*
HXS 00001 1
bit+
'
ID b
STO
;
NEXTX
::
CK0
ID j
DUPDUP
HXS 00001 1
bit+
'
ID j
STO
ID a
bit*
ID b
bit+
HXS 00001 1
SWAP
WORDSIZE
#1-
ONE_DO
DUPUNROT
bit*
SWAPDUP
bit*
LOOP
DROP
bit*
;
NEXTR
::
CK0
ID NEXTX
HXS>%
%2
WORDSIZE
FPTR2 ^RP#
%/
;