func root(n string, base int) (persistence, root int, err error) {
i, err := digit.Sum(n, base)
if err != nil {
return 0, 0, err
}
if len(n) == 1 {
return 0, int(i), nil
}
for {
persistence++
n := strconv.FormatInt(i, base)
if len(n) == 1 {
root = int(i)
break
}
i, _ = digit.Sum(n, base)
}
return
}
func testSum(t *testing.T) {
for _, tc := range testData {
ds, err := digit.Sum(tc.n, tc.base)
if err != nil {
t.Fatal("test case", tc, err)
}
if ds != tc.dSum {
t.Fatal("test case", tc, "got", ds, "expected", tc.dSum)
}
}
}