81 lines
1.8 KiB
Plaintext
81 lines
1.8 KiB
Plaintext
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(* ************************************
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Генератор какбыслучайных чисел,
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Линейный конгруэнтный метод,
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алгоритм Лемера.
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Вадим Исаев, 2020
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-------------------------------
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Generator pseudorandom numbers,
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Linear congruential generator,
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Algorithm by D. H. Lehmer.
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Vadim Isaev, 2020
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*************************************** *)
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MODULE Rand;
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IMPORT HOST, Math;
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CONST
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RAND_MAX = 2147483647;
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VAR
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seed: INTEGER;
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PROCEDURE Randomize*;
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BEGIN
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seed := HOST.GetTickCount()
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END Randomize;
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(* Целые какбыслучайные числа до RAND_MAX *)
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PROCEDURE RandomI* (): INTEGER;
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CONST
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a = 630360016;
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BEGIN
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seed := (a * seed) MOD RAND_MAX
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RETURN seed
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END RandomI;
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(* Какбыслучайные числа с плавающей запятой от 0 до 1 *)
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PROCEDURE RandomR* (): REAL;
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RETURN FLT(RandomI()) / FLT(RAND_MAX)
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END RandomR;
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(* Какбыслучайное число в диапазоне от 0 до l.
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Return a random number in a range 0 ... l *)
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PROCEDURE RandomITo* (aTo: INTEGER): INTEGER;
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RETURN FLOOR(RandomR() * FLT(aTo))
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END RandomITo;
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(* Какбыслучайное число в диапазоне.
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Return a random number in a range *)
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PROCEDURE RandomIRange* (aFrom, aTo: INTEGER): INTEGER;
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RETURN FLOOR(RandomR() * FLT(aTo - aFrom)) + aFrom
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END RandomIRange;
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(* Какбыслучайное число. Распределение Гаусса *)
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PROCEDURE RandG* (mean, stddev: REAL): REAL;
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VAR
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U, S: REAL;
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BEGIN
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REPEAT
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U := 2.0 * RandomR() - 1.0;
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S := Math.sqrr(U) + Math.sqrr(2.0 * RandomR() - 1.0)
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UNTIL (1.0E-20 < S) & (S <= 1.0)
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RETURN Math.sqrt(-2.0 * Math.ln(S) / S) * U * stddev + mean
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END RandG;
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BEGIN
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seed := 654321
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END Rand.
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