got guess function to work for example from book

it calculates (hard coded) the example from the book.  Next step is
making it take any string, calculate the character frequency and then do
the same calculation and print out top answers

main.go

@@ -106,7 +106,7 @@ func main() {
 	}
 
 	var vig = &cobra.Command{
-		Use:   "vig mode -c [cipher] -k [key] -i [input]",
+		Use:   "vig",
 		Short: "vignenere cipher",
 		Long:  `perform vigenere cipher`,
 		Run: func(cmd *cobra.Command, args []string) {
@@ -122,6 +122,19 @@ func main() {
 		},
 	}
 
+	var guess = &cobra.Command{
+		Use:   "guess",
+		Short: "guess cipher",
+		Long:  `will try to guess ceasar cipher`,
+		Run: func(cmd *cobra.Command, args []string) {
+			if len(args) < 1 {
+				fmt.Println("missing input, see -h (--help) for more info")
+				os.Exit(1)
+			}
+			psyfer.Guess()
+		},
+	}
+
 	var random = &cobra.Command{
 		Use:   "random",
 		Short: "randomly transpose",
@@ -236,7 +249,7 @@ func main() {
 	)
 
 	var rootCmd = &cobra.Command{Use: "app"}
-	rootCmd.AddCommand(sub, aes, trans, vig)
+	rootCmd.AddCommand(sub, aes, trans, vig, guess)
 	trans.AddCommand(random, railfence, split)
 	rootCmd.Execute()
 }

psyfer/guess.go

@@ -0,0 +1,79 @@
+package psyfer
+
+import (
+	"fmt"
+	"math"
+	"sort"
+)
+
+var charFreq = []float64{
+	0.080,
+	0.015,
+	0.030,
+	0.040,
+	0.130,
+	0.020,
+	0.015,
+	0.060,
+	0.065,
+	0.005,
+	0.005,
+	0.035,
+	0.030,
+	0.070,
+	0.080,
+	0.020,
+	0.002,
+	0.065,
+	0.060,
+	0.090,
+	0.030,
+	0.010,
+	0.015,
+	0.005,
+	0.020,
+	0.002,
+}
+
+func pc(position, i int) int {
+	if position-i < 0 {
+		return 26 - (int(math.Abs(float64((position - i) % 26))))
+	} else {
+		return int(math.Abs(float64((position - i) % 26)))
+	}
+}
+
+func (p phi) String() string {
+	return fmt.Sprintf("%d %f\n", p.position, p.value)
+}
+
+type phi struct {
+	position int
+	value    float64
+}
+
+type allPhi []phi
+
+func (p allPhi) Len() int           { return len(p) }
+func (p allPhi) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
+func (p allPhi) Less(i, j int) bool { return p[i].value < p[j].value }
+
+func Guess() {
+	fmt.Println((6 - 7) % 26)
+	total := []phi{}
+	for i := 0; i < 26; i++ {
+		a := 0.0
+		a += 0.1 * charFreq[pc(6, i)]
+		a += 0.1 * charFreq[pc(7, i)]
+		a += 0.1 * charFreq[pc(10, i)]
+		a += 0.3 * charFreq[pc(14, i)]
+		a += 0.2 * charFreq[pc(17, i)]
+		a += 0.1 * charFreq[pc(20, i)]
+		a += 0.1 * charFreq[pc(25, i)]
+		p := phi{i, a}
+		total = append(total, p)
+	}
+	fmt.Println(total)
+	sort.Sort(allPhi(total))
+	fmt.Println(total)
+}