Title of program: SRNG ly increasing numbers. Such random integers are used to specify the positions of randomly dispersed impurity atoms or catalogue number: ACIE solute atoms in many computer simulation experiments. A Program obtainable from: CPC Program Library, Queen's Uni-specific case is that of solid solution strengthening. versity of Belfast, N. Ireland (see application form in this issue). Method of solutiopi In order to produce a large subset of sequentially increasing, computer: UNIVAC 1108; Installation: University of non-repeating random integers from a larger set of integers, Maryland, College Park, Maryland, U.S.A. each integer of the larger set is represented by a bit of a corn-Operating system: UNIVAC 1108 EXEC puter word. On the UNIVAC 1108, 35 bits can be used to represent 35 integers of the larger set, the remaining sign bit is Program language used: FORTRAN used to indicate a particular word location. High speed storage required: 17000 words. Two groups of random numbers are generated, which are uniformly distributed in the interval 0 to 1. Group I is used No. of bits in a word: 36 to choose the computer word, and Group 2 is used to choose Overlay structure: None the bit within the computer word. No. of magnetic tapes required: Optional Restrictions on the complexity of the problem The number of integers from which the random subset can be Other peripherals used: Card reader, line printer chosen is limited by the size of the computational cell. The No. of cards in combined program and test deck: 106 cell is limited by the computer storage capacity. card punching code: IBM 029 Typical running time To select a sequential subset of 2.8 X IO 4 non-repeating ran-Keywords: General, random integer, generator, solid solution dorn integers from a larger set of 2.8 X 106 integers requires strengthening.
-15 minutes of UNIVAC 1108 memory time. However,
Nature of physical problem
changing the total number of integers does not result in a un-An algorithm to generate a subset of random integers from a ear change in the computer time. The time required to select larger set of integers has been developed to minimize both the a subset of 2.8 X l0~sequential non-repeating random intecomputing time and the memory space. The algorithm deals gers from a larger set of 2.8 x IO~integers is -3 seconds.
with the whole array at the same time, generates a subset of Unusual features of the program random integers for a given percentage of the range, and the Two unusual features of this program are the use of one's generated subset of random integers is obtained as sequentialcompliment representation of minus zero and bit manipulation capability in the UNIVAC 1108 computer.