Sub GetArrayDimensions( _
   ByVal index As Integer, _
   ByRef rows As Integer, _
   ByRef columns As Integer _
) 

void GetArrayDimensions( 
   int index,
   out int rows,
   out int columns
)

using System;
using SpreadsheetGear;
 
namespace ConsoleApplication
{
    /// <summary>
    /// Demonstrate a custom function which sums the range of cells or values passed to it.
    /// </summary>
    class Program
    {
        static void Main(string[] args)
        {
            // Create a new empty workbook.
            IWorkbookSet workbookSet = Factory.GetWorkbookSet();
            
            // Add the custom function to the workbook set. 
            workbookSet.Add(MySum.MySumSingleton);
 
            // Add a workbook to the workbook set.
            IWorkbook workbook = workbookSet.Workbooks.Add();
        
            // Get the first sheet and it's cells
            SpreadsheetGear.IWorksheet worksheet = workbook.Worksheets[0]; 
            SpreadsheetGear.IRange cells = worksheet.Cells;
        
            // Assign values and formulas to cells.
            cells["A1"].Value = 1; 
            // The OFFSET(...) function enables creation of a range equal to 
            // the number of rows which have values in column A and one column.
            cells["B1"].Formula = "=MYSUM(OFFSET(A1,0,0,COUNT(A:A),1))";
 
            Console.WriteLine("Result calculated from MYSUM  =  " + cells["B1"].Value + " (should be 1).");
 
            // Add another value to column A.
            cells["A2"].Value = 2;
 
            Console.WriteLine("Result calculated from MYSUM  =  " + cells["B1"].Value + " (should be 3).");
        }
    }
    
    // A simple SUM custom function. 
    public class MySum : SpreadsheetGear.CustomFunctions.Function 
    { 
        // Set to the one and only instance of MySum. 
        public static readonly MySum MySumSingleton = new MySum(); 
  
        // Sum the numbers in a range or array. 
        public override void Evaluate( 
            SpreadsheetGear.CustomFunctions.IArguments arguments, 
            SpreadsheetGear.CustomFunctions.IValue result) 
        { 
            // Verify that there are two arguments. 
            if (arguments.Count == 1)
            {
                int rowCount;
                int colCount;
                arguments.GetArrayDimensions(0, out rowCount, out colCount);
                double[,] numbers = new double[rowCount, colCount];
                for (int row = 0; row < rowCount; row++)
                {
                    for (int col = 0; col < colCount; col++)
                    {
                        SpreadsheetGear.CustomFunctions.IValue value = arguments.GetArrayValue(0, row, col);
                        if (value.Type == SpreadsheetGear.CustomFunctions.ValueType.Number)
                            numbers[row, col] = value.Number;
                    }
                }
                // Get the two arguments as numbers, and sum them. 
                result.Number = SumThem(numbers);
            }
            else
                // Return ValueError.Value. 
                result.Error = SpreadsheetGear.ValueError.Value; 
        }
 
        private double SumThem(double[,] numbers)
        {
            double sum = 0.0;
            int rowCount = numbers.GetUpperBound(0) + 1;
            int colCount = numbers.GetUpperBound(1) + 1;
            for (int row = 0; row < rowCount; row++)
                for (int col = 0; col < colCount; col++)
                    sum += numbers[row, col];
            return sum;
        }
 
        // Singleton class - so make the constructor private. 
        private MySum() 
            : base( 
            // The name of the custom function. 
            "MYSUM", 
            // For a given set of inputs, this function always returns the same value. 
            SpreadsheetGear.CustomFunctions.Volatility.Invariant, 
            // This function returns a number. 
            SpreadsheetGear.CustomFunctions.ValueType.Number) 
        { 
        } 
    }
}

Imports System
Imports SpreadsheetGear
 
Namespace ConsoleApplication
    _
    '/ <summary>
    '/ Demonstrate a custom function which sums the range of cells or values passed to it.
    '/ </summary>
    Class Program
 
        'Entry point which delegates to C-style main Private Function
        Public Overloads Shared Sub Main()
            ' Create a new empty workbook.
            Dim workbookSet As IWorkbookSet = Factory.GetWorkbookSet()
 
            ' Add the custom function to the workbook set. 
            workbookSet.Add(MySum.MySumSingleton)
 
            ' Add a workbook to the workbook set.
            Dim workbook As IWorkbook = workbookSet.Workbooks.Add()
 
            ' Get the first sheet and it's cells
            Dim worksheet As SpreadsheetGear.IWorksheet = workbook.Worksheets(0)
            Dim cells As SpreadsheetGear.IRange = worksheet.Cells
 
            ' Assign values and formulas to cells.
            cells("A1").Value = 1
            ' The OFFSET(...) function enables creation of a range equal to 
            ' the number of rows which have values in column A and one column.
            cells("B1").Formula = "=MYSUM(OFFSET(A1,0,0,COUNT(A:A),1))"
 
            Console.WriteLine(("Result calculated from MYSUM  =  " + cells("B1").Text + " (should be 1)."))
 
            ' Add another value to column A.
            cells("A2").Value = 2
 
            Console.WriteLine(("Result calculated from MYSUM  =  " + cells("B1").Text + " (should be 3)."))
        End Sub 'Main
    End Class 'Program
    _
 
    ' A simple SUM custom function. 
    Public Class MySum
        Inherits SpreadsheetGear.CustomFunctions.Function
        ' Set to the one and only instance of MySum. 
        Public Shared MySumSingleton As New MySum()
 
 
        ' Sum the numbers in a range or array. 
        Public Overrides Sub Evaluate(ByVal arguments As SpreadsheetGear.CustomFunctions.IArguments, ByVal result As SpreadsheetGear.CustomFunctions.IValue)
            ' Verify that there are two arguments. 
            If arguments.Count = 1 Then
                Dim rowCount As Integer
                Dim colCount As Integer
                arguments.GetArrayDimensions(0, rowCount, colCount)
                Dim numbers(rowCount, colCount) As Double
                Dim row As Integer
                For row = 0 To rowCount - 1
                    Dim col As Integer
                    For col = 0 To colCount - 1
                        Dim value As SpreadsheetGear.CustomFunctions.IValue = arguments.GetArrayValue(0, row, col)
                        If value.Type = SpreadsheetGear.CustomFunctions.ValueType.Number Then
                            numbers(row, col) = value.Number
                        End If
                    Next col
                Next row ' Get the two arguments as numbers, and sum them. 
                result.Number = SumThem(numbers)
                ' Return ValueError.Value. 
            Else
                result.Error = SpreadsheetGear.ValueError.Value
            End If
        End Sub 'Evaluate
 
        Private Function SumThem(ByVal numbers(,) As Double) As Double
            Dim sum As Double = 0.0
            Dim rowCount As Integer = numbers.GetUpperBound(0) + 1
            Dim colCount As Integer = numbers.GetUpperBound(1) + 1
            Dim row As Integer
            For row = 0 To rowCount - 1
                Dim col As Integer
                For col = 0 To colCount - 1
                    sum += numbers(row, col)
                Next col
            Next row
            Return sum
        End Function 'SumThem
 
 
        ' Singleton class - so make the constructor private. 
        Private Sub New()
            ' The name of the custom function. 
            MyBase.New("MYSUM", SpreadsheetGear.CustomFunctions.Volatility.Invariant, SpreadsheetGear.CustomFunctions.ValueType.Number)
        End Sub 'New ' For a given set of inputs, this function always returns the same value. 
    End Class 'MySum
End Namespace 'ConsoleApplication ' This function returns a number.