RosettaCodeData/Task/Arithmetic-derivative/Go/arithmetic-derivative.go

47 lines
827 B
Go

package main
import (
"fmt"
"rcu"
)
func D(n float64) float64 {
if n < 0 {
return -D(-n)
}
if n < 2 {
return 0
}
var f []int
if n < 1e19 {
f = rcu.PrimeFactors(int(n))
} else {
g := int(n / 100)
f = rcu.PrimeFactors(g)
f = append(f, []int{2, 2, 5, 5}...)
}
c := len(f)
if c == 1 {
return 1
}
if c == 2 {
return float64(f[0] + f[1])
}
d := n / float64(f[0])
return D(d)*float64(f[0]) + d
}
func main() {
ad := make([]int, 200)
for n := -99; n < 101; n++ {
ad[n+99] = int(D(float64(n)))
}
rcu.PrintTable(ad, 10, 4, false)
fmt.Println()
pow := 1.0
for m := 1; m < 21; m++ {
pow *= 10
fmt.Printf("D(10^%-2d) / 7 = %.0f\n", m, D(pow)/7)
}
}