diff --git a/f2.go b/f2.go index 3dbe89b..7c8f53f 100644 --- a/f2.go +++ b/f2.go @@ -26,6 +26,9 @@ type Dist struct { // Parse line into Distribution func parseLineErr(err_msg string) (string, Dist, error) { + general_err_msg := "Valid inputs: 2 || * 2 || / 2 || 2 20 || * 2 20 || / 2 20 || i || e" + fmt.Println(general_err_msg) + fmt.Println(err_msg) return "", Dist{}, errors.New(err_msg) } func parseLine(line string) (string, Dist, error) { @@ -51,11 +54,11 @@ func parseLine(line string) (string, Dist, error) { switch len(words) { case 0: - return parseLineErr("Can't operate on nothing") + return parseLineErr("Operator must have operand; can't operate on nothing") case 1: single_float, err1 := strconv.ParseFloat(words[0], 64) if err1 != nil { - fmt.Println("Trying to operate on a scalar, but scalar is not a float") + return parseLineErr("Trying to operate on a scalar, but scalar is not a float") } dist = Dist{Type: "Lognormal", Lognormal: Lognormal{low: single_float, high: single_float}, Samples: nil} case 2: @@ -75,36 +78,27 @@ func parseLine(line string) (string, Dist, error) { // 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) +func multiplyLogDists(l1 Lognormal, l2 Lognormal) Lognormal { + logmean1 := (math.Log(l1.high) + math.Log(l1.low)) / 2.0 + logstd1 := (math.Log(l1.high) - math.Log(l1.low)) / (2.0 * NORMAL90CONFIDENCE) - logmean_product, logstd_product := multiplyLogParams(logmean_old, logstd_old, logmean_new, logstd_new) + logmean2 := (math.Log(l2.high) + math.Log(l2.low)) / 2.0 + logstd2 := (math.Log(l2.high) - math.Log(l2.low)) / (2.0 * NORMAL90CONFIDENCE) + + logmean_product := logmean1 + logmean2 + logstd_product := math.Sqrt(logstd1*logstd1 + logstd2*logstd2) + + h := logstd_product * NORMAL90CONFIDENCE + loglow := logmean_product - h + loghigh := logmean_product + h + return Lognormal{low: math.Exp(loglow), high: math.Exp(loghigh)} - return logParamsToLogBounds(logmean_product, logstd_product) } func joinDists(old_dist Dist, new_dist Dist, op string) (Dist, error) { 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}, nil + return Dist{Type: "Lognormal", Lognormal: multiplyLogDists(old_dist.Lognormal, new_dist.Lognormal), Samples: nil}, nil default: fmt.Printf("For now, can't do anything besides multiplying lognormals\n") }