golang: Why do I get +Inf instead of an integer or a float?

I am learning golang, working on time value of money computations

I am trying to compute for number of period to say, double your money. The formula that I am using is period = log(fv/pv) / log(1 + i). What I have so far is...

package main
import (
    "fmt"
    "math"
)
var (
    interest,
    futureValue,
    period,
    presentValue float64
)
var rate float64 = interest / 100 //converts interest into decimal... interest / 100
var ratex float64 = 1 + interest //used for (1 + i)

func main() {
    numPeriod()
}
func numPeriod() {
    fmt.Println("Enter interest amount: ")
    fmt.Scanf("%g", &interest)
    fmt.Println("Enter present value: ")
    fmt.Scanf("%g", &presentValue)
    fmt.Println("Enter future value: ")
    fmt.Scanf("%g", &futureValue)
    var logfvpvFactor float64 = futureValue / presentValue
    var logi float64 = math.Log(ratex)
    var logfvpv float64 = math.Log(logfvpvFactor)
    period = logfvpv / logi
    fmt.Printf("Number of period/s is = %g\n", period)
}

Running this, I get...

Number of period/s is = +Inf

...the answer I was looking for is either an integer or a float. How do I get that?

Thanks for your help!