Category talk:Wren-math: Difference between revisions
Added efficient divisorSum, divisorCount and reverse methods to Int class.
(Added modMul, modPow, modInv and isPrime2 (using Miller-Rabin) methods to Int class.) |
(Added efficient divisorSum, divisorCount and reverse methods to Int class.) |
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Line 655:
var c = d.count
return (c <= 1) ? [] : d[0..-2]
}
// Returns the sum of all the divisors of 'n' including 1 and 'n' itself.
static divisorSum(n) {
if (!n.isInteger || n < 1) return 0
var total = 1
var power = 2
while (n % 2 == 0) {
total = total + power
power = 2 * power
n = div(n, 2)
}
var i = 3
while (i * i <= n) {
var sum = 1
power = i
while (n % i == 0) {
sum = sum + power
power = i * power
n = div(n, i)
}
total = total * sum
i = i + 2
}
if (n > 1) total = total * (n + 1)
return total
}
// Returns the number of divisors of 'n' including 1 and 'n' itself.
static divisorCount(n) {
if (!n.isInteger || n < 1) return 0
var count = 0
var prod = 1
while (n % 2 == 0) {
count = count + 1
n = div(n, 2)
}
prod = prod * (1 + count)
var i = 3
while (i * i <= n) {
count = 0
while (n % i == 0) {
count = count + 1
n = div(n, i)
}
prod = prod * (1 + count)
i = i + 2
}
if (n > 2) prod = prod * 2
return prod
}
Line 710 ⟶ 760:
static digitalRoot(n, b) { digitalRoot(n, b, false) }
static digitalRoot(n) { digitalRoot(n, 10, false) }
// Returns a new integer formed by reversing the base 10 digits of 'n'.
// Works with positive, negative and zero integers.
static reverse(n) {
var m = (n >= 0) ? n : -n
var r = 0
while (m > 0) {
r = 10*r + m%10
m = div(m, 10)
}
return r * n.sign
}
// Returns the unique non-negative integer that is associated with a pair
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