random-tools.js

export function getUniform(max = 1, min = 0){
	return min + Math.random() * (max - min);
}

//Box Muller
export function getNormal(mean = 0, standardDeviation = 1) {
	const u1 = Math.random();
	const u2 = Math.random();
	return Math.sqrt(-2 * Math.log(u1)) * Math.cos(2 * Math.PI * u2) * standardDeviation + mean;
}

export function getInt(max = 1, min = 0){
	return Math.floor(getUniform(max, min));
}

export function getBool(){
	return getInt(2) === 0;
}

export function getOption(optionList){
	const index = getInt(optionList.length);
	return optionList[index];
}

const sliceHex = (arr, start, end) =>
	Array.from(arr).slice(start, end).map(x => x.toString(16).toUpperCase().padStart(2, "0")).join("");


export function getGuid(){
	const arr = new Uint8Array(16);
	crypto.getRandomValues(arr);
	return `${sliceHex(arr,0,4)}-${sliceHex(arr,4,6)}-${sliceHex(arr,6,8)}-${sliceHex(arr,8,10)}-${sliceHex(arr,10,16)}`;
}

/**
 * 
 * @param {number} seed 
 * @param {number} start 
 * @param {number} end
 * @description (Park Miller) seed should be greater than 0 and less than 0x7fffffff, output is 32-bit
 */
export function* getRandom(seed = 1, start = 0, end = 1){
	const mod = 0x7fffffff;
	let state = seed % mod;
	const length = (end - start) / mod;
	while(true){
		state = (16807 * state) % mod;
		yield (length * value) + start;
	}
}