Percentiles

percentile(input: any[] | Mat | Tensor, x: Number) : any[]

param input a JS array, matrix or tensor

param x a number between interval [0, 100]

returns - any[] - an array representing the percentile (all the numbers with index larger than x% of the values)

The percentile of a construct, whether it be a function or in our case, arrays, is a description or number for where values in an array below a certain percentage, namely, x, fall below. For example, the 60th percentile is the number where below 60% of all the scores may be found. So if we had [1,2,3,4,5,6,7,8,9,10], the 60th percentile would be '6' and everything below it. Note that the percentile is similar to the quantile.

Hence, in this function, we return an array that contains all the values below the percentile including the percentile value too. So in the 60th percentile case, we would return the array [1,2,3,4,5,6]. Because out of all the values in the array, these are the 60% bottom values.

This aligns well with our modern concept of the word 'percentile'. For example the statement 'he score in the 99th percentile in his exam' we understand to be the top 1%. This makes sense according to the definition we use, as his score is equal to 99% of other scores below his.