diff --git a/f2.go b/f2.go index a50928f..4ad550a 100644 --- a/f2.go +++ b/f2.go @@ -2,13 +2,17 @@ package main import ( "bufio" + "errors" "fmt" + // "math" "os" // "strconv" "strings" ) +const NORMAL90CONFIDENCE = 1.6448536269514727 + // Actually, I should look up how do do a) enums in go, b) union types type Lognormal struct { low float64 @@ -21,21 +25,83 @@ type Dist struct { Samples []float64 } +// Parse line into Distribution, func parseLine(line string) (string, Dist, error) { words := strings.Split(strings.TrimSpace(line), " ") + op = "" + var dist Dist - switch { - case len(words) == 2 && words[0] == "*": - fmt.Printf("Hello world") + switch words[0] { + case "*": + op = "*" + case "/": + op = "/" + case "+": + return "", Dist{}, error.New("+ operation not implemented yet") + case "-": + return "", Dist{}, error.New("- operation not implemented yet") + default: + return "", Dist{}, error.New("operation not recognized") } - return "Lognormal", Dist{}, nil + + switch len(words) { + case 1: + return "", Dist{}, error.New("Can't operate on nothing") + case 2: + single_float, err1 := strconv.ParseFloat(words[1], 64) + if err1 != nil { + fmt.Println("Trying to operate on a scalar, but scalar is not a float") + fmt.Println(error_msg_cont) + continue EventForLoop + } + new_low = single_float + new_high = single_float + + } + +} + +// Join distributions +// Multiply lognormals + +func logBoundsToLogParams(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 logParamsToLogBounds(logmean float64, logstd float64) (float64, float64) { + h := logstd * NORMAL90CONFIDENCE + loglow := logmean - h + loghigh := logmean + h + return math.Exp(loglow), math.Exp(loghigh) +} +func multiplyLogParams(logmean1 float64, logstd1 float64, logmean2 float64, logstd2 float64) (float64, float64) { + return logmean1 + logmean2, math.Sqrt(logstd1*logstd1 + logstd2*logstd2) +} +func multiplyLogBounds(old_low, old_high, new_low, new_high float64) (float64, float64) { + logmean_old, logstd_old := logBoundsToLogParams(old_low, old_high) + logmean_new, logstd_new := logBoundsToLogParams(new_low, new_high) + + logmean_product, logstd_product := multiplyLogParams(logmean_old, logstd_old, logmean_new, logstd_new) + + return logParamsToLogBounds(logmean_product, logstd_product) } func joinDists(old_dist Dist, new_dist Dist, op string) (Dist, error) { - return old_dist, nil + switch { + case old_dist.Type == "Lognormal" && new_dist.Type == "Lognormal" && op == "*": + low, high := multiplyLogBounds(old_dist.Lognormal.low, old_dist.Lognormal.high, new_dist.Lognormal.low, new_dist.Lognormal.high) + return Dist{Type: "Lognormal", Lognormal: Lognormal{low: low, high: high}, Samples: nil} + default: + fmt.Printf("For now, can't do anything besides multiplying lognormals") + } + return old_dist, errors.New("Error blah blah") } +/* Main event loop */ func main() { reader := bufio.NewReader(os.Stdin) old_dist := Dist{Type: "Lognormal", Lognormal: Lognormal{low: 1, high: 1}, Samples: nil} // Could also just be a scalar