102 lines
3.0 KiB
Go
102 lines
3.0 KiB
Go
/*
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Copyright © 2025 filifa
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package cmd
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import (
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"fmt"
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"math/big"
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"github.com/spf13/cobra"
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"scm.dairydemon.net/filifa/mathtools/internal/lib"
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)
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var modulus string
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var tpf []string
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func count(tpf []string) map[string]*big.Int {
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counter := make(map[string]*big.Int)
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for _, s := range tpf {
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count, ok := counter[s]
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if ok {
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count.Add(count, big.NewInt(1))
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} else {
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counter[s] = big.NewInt(1)
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}
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}
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return counter
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}
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func primitiveRoot(cmd *cobra.Command, args []string) {
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m, ok := new(big.Int).SetString(modulus, 10)
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if !ok {
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cobra.CheckErr("invalid input " + modulus)
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}
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factors := count(tpf)
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root := new(big.Int)
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var err error
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if len(factors) == 0 {
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root, err = lib.PrimitiveRoot(m)
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if err != nil {
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cobra.CheckErr(err)
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}
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} else {
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root, err = lib.PrimitiveRootFast(m, factors)
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if err != nil {
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cobra.CheckErr(err)
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}
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}
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fmt.Println(root)
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}
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// primitiveRootCmd represents the primitiveRoot command
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var primitiveRootCmd = &cobra.Command{
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Use: "primitive-root -m M",
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Short: "Compute a primitive root modulo n",
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Long: `Compute a primitive root modulo n.
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This command computes a value g such that, for all integers a coprime to n, g^k = a (mod n) for some k. In other words, this command computes a generator for the multiplicative group of integers modulo n.
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For improved performance, provide the prime factorization of the totient of n with the -t flag.
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Note that primitive roots only exist for the moduli 1, 2, 4, p^k, and 2p^k, where p is an odd prime. The totients of these numbers are 1, 1, 2, (p-1)*p^(k-1), and (p-1)*p^(k-1), respectively.`,
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Run: primitiveRoot,
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}
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func init() {
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rootCmd.AddCommand(primitiveRootCmd)
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// Here you will define your flags and configuration settings.
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// Cobra supports Persistent Flags which will work for this command
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// and all subcommands, e.g.:
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// primitiveRootCmd.PersistentFlags().String("foo", "", "A help for foo")
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// Cobra supports local flags which will only run when this command
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// is called directly, e.g.:
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// primitiveRootCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
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primitiveRootCmd.Flags().StringVarP(&modulus, "modulus", "m", "", "modulus")
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primitiveRootCmd.MarkFlagRequired("modulus")
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primitiveRootCmd.Flags().StringSliceVarP(&tpf, "totient-factorization", "t", make([]string, 0), "prime factorization of the totient of the modulus")
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// TODO: add a check flag for verifying -t input is the totient, test for performance
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}
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