Special factorials: Difference between revisions
Added Go
m (use Int128 to prevent overflow) |
(Added Go) |
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Line 115:
rf(3628800) = 10
rf(119) = f
</pre>
=={{header|Go}}==
{{trans|Wren}}
<lang go>package main
import (
"fmt"
"math/big"
)
func sf(n int) *big.Int {
if n < 2 {
return big.NewInt(1)
}
sfact := big.NewInt(1)
fact := big.NewInt(1)
for i := 2; i <= n; i++ {
fact.Mul(fact, big.NewInt(int64(i)))
sfact.Mul(sfact, fact)
}
return sfact
}
func H(n int) *big.Int {
if n < 2 {
return big.NewInt(1)
}
hfact := big.NewInt(1)
for i := 2; i <= n; i++ {
bi := big.NewInt(int64(i))
hfact.Mul(hfact, bi.Exp(bi, bi, nil))
}
return hfact
}
func af(n int) *big.Int {
if n < 1 {
return new(big.Int)
}
afact := new(big.Int)
fact := big.NewInt(1)
sign := new(big.Int)
if n%2 == 0 {
sign.SetInt64(-1)
} else {
sign.SetInt64(1)
}
t := new(big.Int)
for i := 1; i <= n; i++ {
fact.Mul(fact, big.NewInt(int64(i)))
afact.Add(afact, t.Mul(fact, sign))
sign.Neg(sign)
}
return afact
}
func ef(n int) *big.Int {
if n < 1 {
return big.NewInt(1)
}
t := big.NewInt(int64(n))
return t.Exp(t, ef(n-1), nil)
}
func rf(n *big.Int) int {
i := 0
fact := big.NewInt(1)
for {
if fact.Cmp(n) == 0 {
return i
}
if fact.Cmp(n) > 0 {
return -1
}
i++
fact.Mul(fact, big.NewInt(int64(i)))
}
}
func main() {
fmt.Println("First 10 superfactorials:")
for i := 0; i < 10; i++ {
fmt.Println(sf(i))
}
fmt.Println("\nFirst 10 hyperfactorials:")
for i := 0; i < 10; i++ {
fmt.Println(H(i))
}
fmt.Println("\nFirst 10 alternating factorials:")
for i := 0; i < 10; i++ {
fmt.Print(af(i), " ")
}
fmt.Println("\n\nFirst 5 exponential factorials:")
for i := 0; i <= 4; i++ {
fmt.Print(ef(i), " ")
}
fmt.Println("\n\nThe number of digits in 5$ is", len(ef(5).String()))
fmt.Println("\nReverse factorials:")
facts := []int64{1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800, 119}
for _, fact := range facts {
bfact := big.NewInt(fact)
rfact := rf(bfact)
srfact := fmt.Sprintf("%d", rfact)
if rfact == -1 {
srfact = "none"
}
fmt.Printf("%4s <- rf(%d)\n", srfact, fact)
}
}</lang>
{{out}}
<pre>
First 10 superfactorials:
1
1
2
12
288
34560
24883200
125411328000
5056584744960000
1834933472251084800000
First 10 hyperfactorials:
1
1
4
108
27648
86400000
4031078400000
3319766398771200000
55696437941726556979200000
21577941222941856209168026828800000
First 10 alternating factorials:
0 1 1 5 19 101 619 4421 35899 326981
First 5 exponential factorials:
1 1 2 9 262144
The number of digits in 5$ is 183231
Reverse factorials:
0 <- rf(1)
2 <- rf(2)
3 <- rf(6)
4 <- rf(24)
5 <- rf(120)
6 <- rf(720)
7 <- rf(5040)
8 <- rf(40320)
9 <- rf(362880)
10 <- rf(3628800)
none <- rf(119)
</pre>
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