97 lines
2.5 KiB
Go
97 lines
2.5 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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)
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func cycle(seq []*big.Int, ch chan *big.Int) {
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n := len(seq)
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for i := 0; true; i = (i + 1) % n {
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ch <- seq[i]
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}
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}
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func gaussianBrackets(x, xprev *big.Int, seq []*big.Int, ch chan *big.Int) {
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c := make(chan *big.Int)
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go cycle(seq, c)
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for a := range c {
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tmp := new(big.Int)
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tmp.Mul(a, x)
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tmp.Add(tmp, xprev)
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xprev.Set(x)
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x.Set(tmp)
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ch <- tmp
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}
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}
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func convergents(cmd *cobra.Command, args []string) {
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a0, ok := new(big.Int).SetString(args[0], 10)
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if !ok {
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cobra.CheckErr("invalid input " + args[0])
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}
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denoms := make([]*big.Int, len(args[1:]))
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for i, d := range args[1:] {
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denoms[i] = new(big.Int)
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_, ok := denoms[i].SetString(d, 10)
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if !ok {
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cobra.CheckErr("invalid input " + d)
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}
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}
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hch := make(chan *big.Int)
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kch := make(chan *big.Int)
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go gaussianBrackets(a0, big.NewInt(1), denoms, hch)
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go gaussianBrackets(big.NewInt(1), big.NewInt(0), denoms, kch)
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r := new(big.Rat)
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for {
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h, k := <-hch, <-kch
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r.SetFrac(h, k)
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fmt.Println(r)
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}
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}
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// FIXME: should support an initial block of non-periodic denominators (will need flags)
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// convergentsCmd represents the convergents command
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var convergentsCmd = &cobra.Command{
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Use: "convergents N N [N ...]",
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Short: "Compute convergents of a periodic continued fraction",
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Long: `Compute convergents of a periodic continued fraction.`,
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Args: cobra.MinimumNArgs(2),
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Run: convergents,
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}
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func init() {
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rootCmd.AddCommand(convergentsCmd)
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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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// convergentsCmd.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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// convergentsCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
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}
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