add totient subcommand

cmd/sieve.go

@@ -0,0 +1,42 @@
+/*
+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 (
+	"github.com/spf13/cobra"
+)
+
+// sieveCmd represents the sieve command
+var sieveCmd = &cobra.Command{
+	Use:   "sieve",
+	Short: "Evaluate functions with sieves",
+	Long:  `Evaluate functions with sieves.`,
+}
+
+func init() {
+	rootCmd.AddCommand(sieveCmd)
+
+	// Here you will define your flags and configuration settings.
+
+	// Cobra supports Persistent Flags which will work for this command
+	// and all subcommands, e.g.:
+	// sieveCmd.PersistentFlags().String("foo", "", "A help for foo")
+
+	// Cobra supports local flags which will only run when this command
+	// is called directly, e.g.:
+	// sieveCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
+}

cmd/totient.go

@@ -0,0 +1,84 @@
+/*
+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"
+	"strconv"
+
+	"github.com/spf13/cobra"
+)
+
+func totientSieve(n int) chan int {
+	totients := make([]int, n)
+	totients[0] = 0
+	totients[1] = 1
+	for i := 2; i < n; i++ {
+		totients[i] = i - 1
+	}
+
+	ch := make(chan int)
+	go func() {
+		for i := 0; i < n; i++ {
+			ch <- totients[i]
+			if i == 0 || i == 1 || totients[i] != i-1 {
+				continue
+			}
+
+			for j := 2 * i; j < n; j += i {
+				totients[j] -= totients[j] / i
+			}
+		}
+
+		close(ch)
+	}()
+
+	return ch
+}
+
+func totient(cmd *cobra.Command, args []string) {
+	n, err := strconv.Atoi(args[0])
+	if err != nil {
+		cobra.CheckErr(err)
+	}
+
+	for v := range totientSieve(n) {
+		fmt.Println(v)
+	}
+}
+
+// totientCmd represents the totient command
+var totientCmd = &cobra.Command{
+	Use:   "totient",
+	Short: "Compute the totient function for all numbers less than n",
+	Long:  `Compute the totient function for all numbers less than n.`,
+	Run:   totient,
+}
+
+func init() {
+	sieveCmd.AddCommand(totientCmd)
+
+	// Here you will define your flags and configuration settings.
+
+	// Cobra supports Persistent Flags which will work for this command
+	// and all subcommands, e.g.:
+	// totientCmd.PersistentFlags().String("foo", "", "A help for foo")
+
+	// Cobra supports local flags which will only run when this command
+	// is called directly, e.g.:
+	// totientCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
+}