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TypeScript - own random number generator (custom implementation)
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In this article, we're going to have a look at how to write own random numbers generator that is based on LCG (Linear congruential generator) algorithm in TypeScript.
In TypeScript, we can implement a custom random number generator by using LCG (Linear congruential generator) algorithm. LCG is one of the oldest and best-known pseudorandom number generator algorithm. We can adjust this implementation to work on int or long.
The linear congruential generator is defined by the recurrence formula:
Where:
Xn+1- new seed,a- multiplier,Xn- current seed (comes from previous calculations),c- incrementer,m- modulus (max integer value).
Note: every time
randomInt()method is called, it is necessary to update seed value.
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class CustomRandom {2
private A: number = 1103515245; // multiplier3
private C: number = 12345; // incrementer4
private M: number = 2147483647; // modulus == max integer value5
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public constructor(private seed: number = Date.now()) { /* Nothing here ... */ }7
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public nextInt = (): number => {9
this.seed = (this.seed * this.A + this.C) % this.M;10
return this.seed;11
};12
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public nextDouble = (): number => {14
const value = this.nextInt();15
return value / this.M;16
};17
}18
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// Usage example 1:21
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const random1 = new CustomRandom(3819201); // 3819201 is example initial seed23
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console.log(random1.nextInt()); // 34832809325
console.log(random1.nextInt()); // 12106595826
console.log(random1.nextInt()); // 79032544527
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// Usage example 2 (values should be different always):30
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const random2 = new CustomRandom();32
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console.log(random2.nextInt()); // 92289257534
console.log(random2.nextInt()); // 111727773435
console.log(random2.nextInt()); // 208493314136
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console.log(random2.nextDouble()); // 0.631695539984710338
console.log(random2.nextDouble()); // 0.571640593265947239
console.log(random2.nextDouble()); // 0.3298228519641901