From e1abdb0e5a0ecae47dd0116c9165f4ad6e492856 Mon Sep 17 00:00:00 2001
From: xuri <xuri.me@gmail.com>
Date: Thu, 25 Mar 2021 00:05:02 +0800
Subject: This closes #809, and add new fn: HARMEAN

---
 calc.go | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

(limited to 'calc.go')

diff --git a/calc.go b/calc.go
index 8be52c7..04d0f8b 100644
--- a/calc.go
+++ b/calc.go
@@ -282,6 +282,7 @@ var tokenPriority = map[string]int{
 //    GAMMA
 //    GAMMALN
 //    GCD
+//    HARMEAN
 //    HEX2BIN
 //    HEX2DEC
 //    HEX2OCT
@@ -3927,6 +3928,40 @@ func (fn *formulaFuncs) GAMMALN(argsList *list.List) formulaArg {
 	return newErrorFormulaArg(formulaErrorVALUE, "GAMMALN requires 1 numeric argument")
 }
 
+// HARMEAN function calculates the harmonic mean of a supplied set of values.
+// The syntax of the function is:
+//
+//    HARMEAN(number1,[number2],...)
+//
+func (fn *formulaFuncs) HARMEAN(argsList *list.List) formulaArg {
+	if argsList.Len() < 1 {
+		return newErrorFormulaArg(formulaErrorVALUE, "HARMEAN requires at least 1 argument")
+	}
+	if min := fn.MIN(argsList); min.Number < 0 {
+		return newErrorFormulaArg(formulaErrorNA, formulaErrorNA)
+	}
+	number, val, cnt := 0.0, 0.0, 0.0
+	for token := argsList.Front(); token != nil; token = token.Next() {
+		arg := token.Value.(formulaArg)
+		switch arg.Type {
+		case ArgString:
+			num := arg.ToNumber()
+			if num.Type != ArgNumber {
+				continue
+			}
+			number = num.Number
+		case ArgNumber:
+			number = arg.Number
+		}
+		if number <= 0 {
+			return newErrorFormulaArg(formulaErrorNA, formulaErrorNA)
+		}
+		val += (1 / number)
+		cnt++
+	}
+	return newNumberFormulaArg(1 / (val / cnt))
+}
+
 // KURT function calculates the kurtosis of a supplied set of values. The
 // syntax of the function is:
 //
-- 
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