sum.ts

// Kahan-Babuska algorithm
export const sum = (x: number[]) => {
  if (x.length === 0) return 0
  let res = x[0], c = 0, t = 0
  for (let i = 1; i < x.length; i++) {
    t = res + x[i]
    if (Math.abs(res) >= Math.abs(x[i])) {
      c += res - t + x[i]
    } else {
      c += x[i] - t + res
    }
    res = t
  }
  return res + c
}