fermi/f.go
2024-05-10 22:38:20 +01:00

126 lines
3.6 KiB
Go

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