84 lines
2.4 KiB
Go
84 lines
2.4 KiB
Go
/*
|
|
Copyright © 2025 filifa
|
|
|
|
This program is free software: you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation, either version 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
package cmd
|
|
|
|
import (
|
|
"fmt"
|
|
"math/big"
|
|
|
|
"github.com/spf13/cobra"
|
|
)
|
|
|
|
var jacobiTop string
|
|
var jacobiBottom string
|
|
|
|
func jacobi(cmd *cobra.Command, args []string) {
|
|
x, ok := new(big.Int).SetString(jacobiTop, 10)
|
|
if !ok {
|
|
cobra.CheckErr("invalid input " + jacobiTop)
|
|
}
|
|
|
|
y, ok := new(big.Int).SetString(jacobiBottom, 10)
|
|
if !ok {
|
|
cobra.CheckErr("invalid input " + jacobiBottom)
|
|
}
|
|
|
|
mod := big.NewInt(2)
|
|
mod.Mod(y, mod)
|
|
if mod.Cmp(big.NewInt(0)) == 0 {
|
|
cobra.CheckErr("modulus must be odd")
|
|
}
|
|
|
|
z := big.Jacobi(x, y)
|
|
fmt.Println(z)
|
|
}
|
|
|
|
// jacobiCmd represents the jacobi command
|
|
var jacobiCmd = &cobra.Command{
|
|
Use: "jacobi -a A -n N",
|
|
Short: "Compute the Jacobi symbol",
|
|
Long: `Compute the Jacobi symbol (a | n).
|
|
|
|
The Jacobi symbol is useful for studying quadratic residues. a is a quadratic residue modulo n if there exists a value x such that
|
|
x^2 = a (mod n)
|
|
|
|
If a is a quadratic residue modulo n and gcd(a, n) = 1, then (a | n) = 1.
|
|
If (a | n) = -1, then a is a quadratic nonresidue modulo n.
|
|
|
|
However, (a | n) = 1 does not guarantee that a is a quadratic residue modulo n.`,
|
|
Run: jacobi,
|
|
}
|
|
|
|
func init() {
|
|
rootCmd.AddCommand(jacobiCmd)
|
|
|
|
// Here you will define your flags and configuration settings.
|
|
|
|
// Cobra supports Persistent Flags which will work for this command
|
|
// and all subcommands, e.g.:
|
|
// jacobiCmd.PersistentFlags().String("foo", "", "A help for foo")
|
|
|
|
// Cobra supports local flags which will only run when this command
|
|
// is called directly, e.g.:
|
|
// jacobiCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
|
|
|
|
jacobiCmd.Flags().StringVarP(&jacobiTop, "residue", "a", "", "residue")
|
|
jacobiCmd.MarkFlagRequired("residue")
|
|
jacobiCmd.Flags().StringVarP(&jacobiBottom, "modulus", "n", "", "modulus")
|
|
jacobiCmd.MarkFlagRequired("modulus")
|
|
}
|