The purpose of this notebook is to walkthrough the algorithm used to compute the flow time.
First we get the current time
const now = new Date()
Then we create a unique identifiers for the current day and hour
const getSeedsFromDate = (date) => {
const year = date.getFullYear()
const month = (date.getMonth() + 1).toString().padStart(2, '0')
const day = date
.getDate() // day of the month
.toString()
.padStart(2, '0')
const hour = date
.getHours()
.toString()
.padStart(2, '0')
return {
minute: parseInt(`${year}${month}${day}${hour}`),
hour: parseInt(`${year}${month}${day}`)
}
}
const seed = getSeedsFromDate(now)
Next we create pseudo-random number generator with the seeds
const createLcg = (seed, modulus, multiplier, increment) => {
const m = modulus
const a = multiplier
const c = increment
let z = seed
return {
rand: () => {
z = (a * z + c) % m
return z / m
}
}
}
const getHourLcg = (seed) => {
// values from the Numerical Recipes book
return createLcg(seed, 4294967296, 1664525, 1013904223)
}
const getMinuteLcg = (seed) => {
// values from MINSTD
return createLcg(seed, 2147483647, 48271, 0)
}
const hourLcg = getHourLcg(seed.hour)
const minuteLcg = getMinuteLcg(seed.minute)
Now we generate the sequence of hours
const getSequenceFromLcg = (lcg, length) => {
const values = []
// generate sequence
for (let i = 0; i < length; i++) {
values.push(lcg.rand())
}
// copy and sort sequence
const sorted = values.slice().sort()
// normalize values based on their order
for (let i = 0; i < sorted.length; i++) {
values[values.indexOf(sorted[i])] = i
}
return values
}
const hourSequence = getSequenceFromLcg(hourLcg, 24)
And the sequence of minutes
const minuteSequence = getSequenceFromLcg(minuteLcg, 60)
Finally we map the date hours and minutes to the sequence we generated to create the flow time
const time = {
hour: hourSequence[now.getHours()],
minute: minuteSequence[now.getMinutes()],
second: now.getSeconds()
}
no comments
sign in to comment