128 lines
3.6 KiB
Go
128 lines
3.6 KiB
Go
package main
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import (
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"bufio"
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"fmt"
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"math"
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"os"
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"strconv"
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"strings"
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)
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const NORMAL90CONFIDENCE = 1.6448536269514727
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func boundsToLogParams(low float64, high float64) (float64, float64) {
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loglow := math.Log(low)
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loghigh := math.Log(high)
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logmean := (loghigh + loglow) / 2.0
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logstd := (loghigh - loglow) / (2.0 * NORMAL90CONFIDENCE)
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return logmean, logstd
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}
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func multiplyLognormals(logmean1 float64, logstd1 float64, logmean2 float64, logstd2 float64) (float64, float64) {
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return logmean1 + logmean2, math.Sqrt(logstd1*logstd1 + logstd2*logstd2)
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}
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func logParamsToBounds(logmean float64, logstd float64) (float64, float64) {
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h := logstd * NORMAL90CONFIDENCE
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loglow := logmean - h
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loghigh := logmean + h
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return math.Exp(loglow), math.Exp(loghigh)
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}
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func combineBounds(old_low, old_high, new_low, new_high float64) (float64, float64) {
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logmean_old, logstd_old := boundsToLogParams(old_low, old_high)
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logmean_new, logstd_new := boundsToLogParams(new_low, new_high)
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logmean_product, logstd_product := multiplyLognormals(logmean_old, logstd_old, logmean_new, logstd_new)
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return logParamsToBounds(logmean_product, logstd_product)
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}
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func main() {
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var old_low, old_high float64
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reader := bufio.NewReader(os.Stdin)
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input, _ := reader.ReadString('\n')
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input = strings.TrimSpace(input)
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tokens := strings.Split(input, " ")
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error_msg_start := "Please enter two floats separated by a space, like: 1 10"
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if len(tokens) != 2 {
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fmt.Println(error_msg_start)
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return
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}
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old_low, err1 := strconv.ParseFloat(tokens[0], 64)
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old_high, err2 := strconv.ParseFloat(tokens[1], 64)
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if err1 != nil || err2 != nil {
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fmt.Println(error_msg_start)
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return
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}
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fmt.Printf("=> %.1f %.1f\n", old_low, old_high)
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error_msg_cont := "Please enter two floats separated by a space, like: 1 10, or two floats preceded by a division, like: / 2 20. Or enter i to get the logmean and logstd"
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EventForLoop:
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for {
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// fmt.Println("Enter another two floats separated by a space:")
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input, _ = reader.ReadString('\n')
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if strings.TrimSpace(input) == "" {
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continue EventForLoop
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}
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tokens := strings.Split(strings.TrimSpace(input), " ")
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var err1, err2 error
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var new_low, new_high float64
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switch len(tokens) {
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case 0:
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continue EventForLoop
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case 1:
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if tokens[0] == "i" {
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fmt.Printf("=> %.1f %.1f\n", old_low, old_high)
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logmean_old, logstd_old := boundsToLogParams(old_low, old_high)
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fmt.Printf("=> Lognormal, with logmean: %.1f, logstd: %.1f\n", logmean_old, logstd_old)
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continue EventForLoop
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}
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fmt.Println(error_msg_cont)
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continue EventForLoop
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case 2:
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new_low, err1 = strconv.ParseFloat(tokens[0], 64)
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new_high, err2 = strconv.ParseFloat(tokens[1], 64)
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if err1 != nil || err2 != nil {
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fmt.Println(error_msg_cont)
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continue EventForLoop
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}
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case 3:
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switch tokens[0] {
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case "*":
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new_low, err1 = strconv.ParseFloat(tokens[1], 64)
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new_high, err2 = strconv.ParseFloat(tokens[2], 64)
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if err1 != nil || err2 != nil {
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fmt.Println(error_msg_cont)
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continue EventForLoop
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}
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case "/":
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new_low, err1 = strconv.ParseFloat(tokens[1], 64)
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new_high, err2 = strconv.ParseFloat(tokens[2], 64)
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if err1 != nil || err2 != nil {
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fmt.Println(error_msg_cont)
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continue EventForLoop
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}
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tmp_low := new_low
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new_low = 1.0 / new_high
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new_high = 1.0 / tmp_low
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default:
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fmt.Println(error_msg_cont)
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continue EventForLoop
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}
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default:
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fmt.Println(error_msg_cont)
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continue EventForLoop
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}
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// Use the abstracted function for combining floats
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old_low, old_high = combineBounds(old_low, old_high, new_low, new_high)
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fmt.Printf("=> %.1f %.1f\n", old_low, old_high)
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}
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}
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