英文:
golang: Why do I get +Inf instead of an integer or a float?
问题
我正在学习golang，正在处理货币时间价值计算。
我正在尝试计算翻倍的时间周期。我使用的公式是period = log(fv/pv) / log(1 + i)。我目前的代码如下：
package main
import (
"fmt"
"math"
)
var (
interest,
futureValue,
period,
presentValue float64
)
var rate float64 = interest / 100 //将利率转换为小数... interest / 100
var ratex float64 = 1 + interest //用于(1 + i)的计算
func main() {
numPeriod()
}
func numPeriod() {
fmt.Println("输入利率金额：")
fmt.Scanf("%g", &interest)
fmt.Println("输入现值：")
fmt.Scanf("%g", &presentValue)
fmt.Println("输入未来值：")
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("时间周期数为 = %g\n", period)
}
运行这段代码，我得到的结果是：
时间周期数为 = +Inf
...我想要的答案应该是一个整数或浮点数。我该如何得到这样的结果？
谢谢你的帮助！
英文:
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!
答案1
得分: 6
为了扩展Diego的答案，你有这一行代码：
var ratex float64 = 1 + interest
在定义interest之前，所以它的值是0，ratex变成了1。然后你有这一行代码：
var logi float64 = math.Log(ratex)
由于ratex是1，而1的对数是0，logi变成了0。然后你通过除以logi来定义period，而logi是0，所以你会得到+inf。
你应该在获取了interest的输入后将值赋给ratex。
英文:
To expand on Diego's answer, you have the line
var ratex float64 = 1 + interest
before interest is defined, so it is 0 and ratex becomes 1. Then you have the line
var logi float64 = math.Log(ratex)
and since ratex is 1, and the log of 1 is 0, logi becomes 0. You then define the period by dividing by logi, which is 0, so you will get +inf.
What you should do is assign the value to ratex after you have gotten the input for what the interest is.
答案2
得分: 2
当你给ratex赋值时，利息为0。因此，增加你的价值所需的时间将是无限的。你想要的是：
func numPeriod() {
fmt.Println("输入利息金额：")
fmt.Scanf("%g", &interest)
var ratex float64 = 1 + interest / 100 //用于(1 + i)
fmt.Println("输入现值：")
fmt.Scanf("%g", &presentValue)
fmt.Println("输入未来值：")
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("期数为 = %g\n", period)
}
英文:
When you assign the value of ratex, interest is 0. Therefore, the time required to increase your value will be infinity. What you want is:
func numPeriod() {
fmt.Println("Enter interest amount: ")
fmt.Scanf("%g", &interest)
var ratex float64 = 1 + interest / 100 //used for (1 + i)
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)
}
答案3
得分: 1
package main
import (
"fmt"
"math"
)
func main() {
var i, pv, fv float64
fmt.Println("输入利息金额：")
fmt.Scanf("%g", &i)
fmt.Println("输入现值：")
fmt.Scanf("%g", &pv)
fmt.Println("输入未来值：")
fmt.Scanf("%g", &fv)
fmt.Printf("期数 = %g\n", math.Log(fv/pv)/math.Log(1+i))
}
英文:
(09:54) jnml@fsc-r550:~/src/tmp/SO/13739751$ cat main.go
package main
import (
"fmt"
"math"
)
func main() {
var i, pv, fv float64
fmt.Println("Enter interest amount: ")
fmt.Scanf("%g", &i)
fmt.Println("Enter present value: ")
fmt.Scanf("%g", &pv)
fmt.Println("Enter future value: ")
fmt.Scanf("%g", &fv)
fmt.Printf("Number of period/s is = %g\n", math.Log(fv/pv)/math.Log(1+i))
}
(09:54) jnml@fsc-r550:~/src/tmp/SO/13739751$ go run main.go
Enter interest amount:
.1
Enter present value:
100
Enter future value:
200
Number of period/s is = 7.272540897341713
(09:54) jnml@fsc-r550:~/src/tmp/SO/13739751$
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