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Sequential random integer generator
C-394 Computer Physics C o m m u n i c a t i o n s 12 (1976) 1 6 3 - 1 7 1 © North-Holland Publishing C o m p a n y
SEQUENTIAL RANDOM INTEGER GENERATOR * C.T.K. KUO
, T.W. C A D M A N
a n d R.J. A R S E N A U L T
University oJ Mao,land, College Park. Maryland 20 742, USA Received 4 October 1976
PROGRAM SUMMARY Title o f program: SRNG Catalogue number: ACIE Computer: UNIVAC 1108; Installation: University of Maryland, College Park, Maryland, U.S.A.
Operating system: UNIVAC 1108 EXEC
ly increasing numbers. Such random integers are used to specify the positions of randomly dispersed impurity atoms or solute atoms in many c o m p u t e r sinlulation experiments. A specific ease is that of solid solution strengthening.
Method of soluthm
Other peripherals used: Card reader, line printer
In order to produce a large subset of sequentially increasing, non-repeating random integers from a larger set of integers, each integer of the larger set is represented by a bit of a computer word. On the UNIVAC 1108, 35 bits can be used to represent 35 integers of the larger set, the remaining sign bit is used to indicate a particular word location. Two groups of r'mdom numbers are generated, which are uniformly distributed in the interval0 to 1. Group I is used to choose the eompt, ter word, and Group 2 is used to choose the bit within the c o m p u t e r word.
No. o f cards in combined program and test deck: 106
Restrictions on the complexity o f the prohlem
Keywords: General, random integer, generator, solid solution
The number of integers from which the r:,ndom subset can be chosen is limited by the size of the computational cell. The cell is limited by the computer storage capacity.
Program language used: F O R T R A N High speed storage required: 17000 words. No. oJ'bits in a word: 36 Overlay structure: None No. o f magnetic tapes required: Opt io nal
strengthening.
Nature o f physical problem
An algorithm to generate a subset of random integers from a larger set of integers has been developed to minimize both the computing time and the m e m o r y space. The algorithm deals with the whole array at the same time, generates a subset o f random integers for a given percentage of the range, and the generated subset of random integers is obtained as sequential* This work was supported by a NASA Grant No. NSG-3001, and the C o m p u t e r Science Center o f the University of Maryland.
Typical running time To select a sequential subset of 2.8 × 104 non-repe:lting random integers froln a larger set of 2.8 × 106 integers rcquircs -.15 minutes of UNIVAC 1108 m e m o r y time. However, changing the total n u m b e r of integers does not result in a linear change in thc computer time. The time required to select a subset of 2.8 × 103 sequential non-repeating random integers from a larger set of 2.8 x 105 intcgersis ~3 scconds.
Unusual features o f the program Two unusual features of this program are the use of one's eolnplimenl representation of minus zero and bit nlanipulation capability in thc UNIVA(" 1108 computer.
SEQUENTIAL RANDOM INTEGER GENERATOR * C.T.K. KUO
, T.W. C A D M A N
a n d R.J. A R S E N A U L T
University oJ Mao,land, College Park. Maryland 20 742, USA Received 4 October 1976
PROGRAM SUMMARY Title o f program: SRNG Catalogue number: ACIE Computer: UNIVAC 1108; Installation: University of Maryland, College Park, Maryland, U.S.A.
Operating system: UNIVAC 1108 EXEC
ly increasing numbers. Such random integers are used to specify the positions of randomly dispersed impurity atoms or solute atoms in many c o m p u t e r sinlulation experiments. A specific ease is that of solid solution strengthening.
Method of soluthm
Other peripherals used: Card reader, line printer
In order to produce a large subset of sequentially increasing, non-repeating random integers from a larger set of integers, each integer of the larger set is represented by a bit of a computer word. On the UNIVAC 1108, 35 bits can be used to represent 35 integers of the larger set, the remaining sign bit is used to indicate a particular word location. Two groups of r'mdom numbers are generated, which are uniformly distributed in the interval0 to 1. Group I is used to choose the eompt, ter word, and Group 2 is used to choose the bit within the c o m p u t e r word.
No. o f cards in combined program and test deck: 106
Restrictions on the complexity o f the prohlem
Keywords: General, random integer, generator, solid solution
The number of integers from which the r:,ndom subset can be chosen is limited by the size of the computational cell. The cell is limited by the computer storage capacity.
Program language used: F O R T R A N High speed storage required: 17000 words. No. oJ'bits in a word: 36 Overlay structure: None No. o f magnetic tapes required: Opt io nal
strengthening.
Nature o f physical problem
An algorithm to generate a subset of random integers from a larger set of integers has been developed to minimize both the computing time and the m e m o r y space. The algorithm deals with the whole array at the same time, generates a subset o f random integers for a given percentage of the range, and the generated subset of random integers is obtained as sequential* This work was supported by a NASA Grant No. NSG-3001, and the C o m p u t e r Science Center o f the University of Maryland.
Typical running time To select a sequential subset of 2.8 × 104 non-repe:lting random integers froln a larger set of 2.8 × 106 integers rcquircs -.15 minutes of UNIVAC 1108 m e m o r y time. However, changing the total n u m b e r of integers does not result in a linear change in thc computer time. The time required to select a subset of 2.8 × 103 sequential non-repeating random integers from a larger set of 2.8 x 105 intcgersis ~3 scconds.
Unusual features o f the program Two unusual features of this program are the use of one's eolnplimenl representation of minus zero and bit nlanipulation capability in thc UNIVA(" 1108 computer.