Rev | Line | |
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[12] | 1 | FUNCTION RNDM (ISEED) |
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| 2 | C |
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| 3 | C CERN PROGLIB# V104 RNDM .VERSION KERNVAX 2.39 930112 |
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| 4 | C ORIG. 22-MAR-88 from IBM version of G.Marsaglia et al., Montreal |
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| 5 | C |
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| 6 | C !!! Version valid only for VAX floating point format !!! |
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| 7 | C Careful: compile with /CHECK=NOOVERFLOW |
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| 8 | C |
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| 9 | C- Uniform Random Number Generator, |
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| 10 | C- giving the same sequence as the IBM and VAX m-language version |
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| 11 | |
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| 12 | EQUIVALENCE (AMAN,MANT) |
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| 13 | PARAMETER (MSK1 = 3072) |
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| 14 | C PARAMETER (MSK1 = '00000C00'X) |
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| 15 | PARAMETER (MSK2 = 13312) |
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| 16 | C PARAMETER (MSK2 = '00003400'X) |
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| 17 | SAVE MCGN |
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| 18 | DATA MCGN /12345/ |
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| 19 | |
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| 20 | |
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| 21 | MCGN = MCGN * 69069 |
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| 22 | MANT = ISHFT (MCGN,-8) |
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| 23 | IF (MANT.EQ.0) GO TO 14 |
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| 24 | AMAN = MANT |
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| 25 | C- AMAN in the range 1 to 2**24-1 |
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| 26 | MANT = MANT - MSK1 |
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| 27 | C- multiply by 2.**(-24) |
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| 28 | RNDM = AMAN |
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| 29 | RETURN |
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| 30 | |
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| 31 | C-- for zero set RNDM = 2.**(-25) |
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| 32 | 14 MANT = MSK2 |
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| 33 | RNDM = AMAN |
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| 34 | RETURN |
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| 35 | |
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| 36 | C-- Integer random number |
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| 37 | ENTRY IRNDM (ISEED) |
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| 38 | MCGN = MCGN * 69069 |
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| 39 | IRNDM = ISHFT (MCGN,-1) |
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| 40 | RETURN |
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| 41 | |
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| 42 | C-- Set the seed |
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| 43 | ENTRY RDMIN (ISEED) |
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| 44 | MCGN = ISEED |
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| 45 | RETURN |
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| 46 | |
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| 47 | C-- Get the seed |
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| 48 | ENTRY RDMOUT (ISEED) |
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| 49 | ISEED = MCGN |
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| 50 | END |
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