LOOKUP can only find exact match

[stanim]

Description

The LOOKUP function only returns a result if it can find an exact match in lookup vector, but does not support:

If the LOOKUP function can't find the lookup_value, the function matches the largest value in lookup_vector that is less than or equal to lookup_value.

If lookup_value is smaller than the smallest value in lookup_vector, LOOKUP returns the #N/A error value.

Important: The values in array must be placed in ascending order: ..., -2, -1, 0, 1, 2, ..., A-Z, FALSE, TRUE; otherwise, LOOKUP might not return the correct value. Uppercase and lowercase text are equivalent.

According to the official Microsoft Excel documentation: https://support.microsoft.com/en-us/office/lookup-function-446d94af-663b-451d-8251-369d5e3864cb

Steps to reproduce the issue:

1. Add a test which looks for the nearest value:

	cellData := [][]interface{}{
		{1, 4, nil, "Month", "Team", "Sales"},
		{2, 5, nil, "Jan", "North 1", 36693},
		{3, nil, nil, "Jan", "North 2", 22100},
		{0, nil, nil, "Jan", "South 1", 53321},
		{nil, nil, nil, "Jan", "South 2", 34440},
		{nil, nil, nil, "Feb", "North 1", 29889},
		{nil, nil, nil, "Feb", "North 2", 50090},
		{nil, nil, nil, "Feb", "South 1", 32080},
		{nil, nil, nil, "Feb", "South 2", 45500},
	}
	mathCalc := map[string]string{
                ...
		"=LOOKUP(F3+1,F3:F4,F3:F4)":    "22100",

2. Run go test.

Describe the results you received:

> go test
--- FAIL: TestCalcCellValue (7.88s)
    calc_test.go:1218: 
        	Error Trace:	calc_test.go:1218
        	Error:      	Received unexpected error:
        	            	LOOKUP no result found
        	Test:       	TestCalcCellValue
        	Messages:   	=LOOKUP(F3+1,F3:F4,F3:F4)
    calc_test.go:1219: 
        	Error Trace:	calc_test.go:1219
        	Error:      	Not equal: 
        	            	expected: "22100"
        	            	actual  : ""
        	            	
        	            	Diff:
        	            	--- Expected
        	            	+++ Actual
        	            	@@ -1 +1 @@
        	            	-22100
        	            	+
        	Test:       	TestCalcCellValue
        	Messages:   	=LOOKUP(F3+1,F3:F4,F3:F4)

Describe the results you expected:

I expected the test to pass.

Output of go version:

go version go1.16.7 linux/amd64

Excelize version or commit ID:

> git log
commit a55f354eb3d0c6c1b9a543ff8ff98227aa6063a6 (HEAD -> lookup, origin/master, origin/HEAD, master)
Author: xuri <xuri.me@gmail.com>
Date:   Tue Aug 17 00:01:44 2021 +0800

    This closes #989, closes #990
    
    New API: `SetRowStyle` support for set style for the rows
    Update documentation for the `GetRows`, `SetCellStyle` and `SetColStyle`

Environment details (OS, Microsoft Excel™ version, physical, etc.):

• OS: Archlinux 5.13.10-arch1-1
• WPS Spreadsheets (version wps-office 11.1.0.10702-1)
• LibreCalc (version libreoffice-fresh 7.1.5-2)

I'll try to make a pull request.