From dca03c6230e596560ea58ca1edb27581cdd59aaa Mon Sep 17 00:00:00 2001
From: Stani <spe.stani.be@gmail.com>
Date: Thu, 19 Aug 2021 16:12:37 +0200
Subject: [PATCH] This closes #994, fix LOOKUP function for Array form

---
 calc.go      | 18 +++++++++++++-----
 calc_test.go |  4 ++++
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/calc.go b/calc.go
index eb6ff759..f52ed538 100644
--- a/calc.go
+++ b/calc.go
@@ -7263,7 +7263,11 @@ func (fn *formulaFuncs) LOOKUP(argsList *list.List) formulaArg {
 	if lookupVector.Type != ArgMatrix && lookupVector.Type != ArgList {
 		return newErrorFormulaArg(formulaErrorVALUE, "LOOKUP requires second argument of table array")
 	}
-	cols, matchIdx := lookupCol(lookupVector), -1
+	arrayForm := lookupVector.Type == ArgMatrix
+	if arrayForm && len(lookupVector.Matrix) == 0 {
+		return newErrorFormulaArg(formulaErrorVALUE, "LOOKUP requires not empty range as second argument")
+	}
+	cols, matchIdx := lookupCol(lookupVector, 0), -1
 	for idx, col := range cols {
 		lhs := lookupValue
 		switch col.Type {
@@ -7280,9 +7284,13 @@ func (fn *formulaFuncs) LOOKUP(argsList *list.List) formulaArg {
 			break
 		}
 	}
-	column := cols
+	var column []formulaArg
 	if argsList.Len() == 3 {
-		column = lookupCol(argsList.Back().Value.(formulaArg))
+		column = lookupCol(argsList.Back().Value.(formulaArg), 0)
+	} else if arrayForm && len(lookupVector.Matrix[0]) > 1 {
+		column = lookupCol(lookupVector, 1)
+	} else {
+		column = cols
 	}
 	if matchIdx < 0 || matchIdx >= len(column) {
 		return newErrorFormulaArg(formulaErrorNA, "LOOKUP no result found")
@@ -7291,13 +7299,13 @@ func (fn *formulaFuncs) LOOKUP(argsList *list.List) formulaArg {
 }
 
 // lookupCol extract columns for LOOKUP.
-func lookupCol(arr formulaArg) []formulaArg {
+func lookupCol(arr formulaArg, idx int) []formulaArg {
 	col := arr.List
 	if arr.Type == ArgMatrix {
 		col = nil
 		for _, r := range arr.Matrix {
 			if len(r) > 0 {
-				col = append(col, r[0])
+				col = append(col, r[idx])
 				continue
 			}
 			col = append(col, newEmptyFormulaArg())
diff --git a/calc_test.go b/calc_test.go
index 54bdc015..ffcdb4db 100644
--- a/calc_test.go
+++ b/calc_test.go
@@ -1131,6 +1131,9 @@ func TestCalcCellValue(t *testing.T) {
 		// LOOKUP
 		"=LOOKUP(F8,F8:F9,F8:F9)":      "32080",
 		"=LOOKUP(F8,F8:F9,D8:D9)":      "Feb",
+		"=LOOKUP(E3,E2:E5,F2:F5)":      "22100",
+		"=LOOKUP(E3,E2:F5)":            "22100",
+		"=LOOKUP(1,MUNIT(1))":          "1",
 		"=LOOKUP(1,MUNIT(1),MUNIT(1))": "1",
 		// ROW
 		"=ROW()":                "1",
@@ -2090,6 +2093,7 @@ func TestCalcCellValue(t *testing.T) {
 		"=LOOKUP()":                     "LOOKUP requires at least 2 arguments",
 		"=LOOKUP(D2,D1,D2)":             "LOOKUP requires second argument of table array",
 		"=LOOKUP(D2,D1,D2,FALSE)":       "LOOKUP requires at most 3 arguments",
+		"=LOOKUP(1,MUNIT(0))":           "LOOKUP requires not empty range as second argument",
 		"=LOOKUP(D1,MUNIT(1),MUNIT(1))": "LOOKUP no result found",
 		// ROW
 		"=ROW(1,2)":          "ROW requires at most 1 argument",