Added new kb article sumproduct-function-nested-array-formulas-telerik-spreadprocessing

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knowledge-base/sumproduct-function-nested-array-formulas-telerik-spreadprocessing.md

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+---
+title: Implementing SUMPRODUCT Function in SpreadProcessing
+description: Explains how to implement a custom SUMPRODUCT function in Telerik SpreadProcessing for results similar to Excel.
+type: how-to
+page_title: SUMPRODUCT Function Implementation in Telerik SpreadProcessing
+meta_title: SUMPRODUCT Function Implementation  in Telerik SpreadProcessing
+slug: sumproduct-function-nested-array-formulas-telerik-spreadprocessing
+tags: spreadprocessing, formula, custom function, sumproduct, array formulas
+res_type: kb
+ticketid: 1694608
+---
+
+## Environment
+
+| Version | Product | Author | 
+| ---- | ---- | ---- | 
+| 2025.2.520| RadSpreadProcessing |[Desislava Yordanova](https://www.telerik.com/blogs/author/desislava-yordanova)| 
+
+## Description
+
+Learn how to implement a custom SUMPRODUCT function that exists in Excel but not in Telerik SpreadProcessing. The function works for basic cases but returns incorrect results for formulas with nested array functions.
+
+## Solution
+
+SpreadProcessing does not natively support full array formula evaluation or Excel-style boolean coercion inside custom functions. To achieve Excel-like results, manually evaluate nested logic before passing data to the custom function, or extend your implementation to handle nested expressions explicitly. Follow the steps below:
+
+1. Register your custom SUMPRODUCT function using the `FunctionManager.RegisterFunction()` method.
+
+2. Implement your custom function as shown below. Ensure it handles simple array inputs correctly.
+
+```csharp
+    internal class Program
+    {
+        static void Main(string[] args)
+        {
+            FunctionManager.RegisterFunction(new SumProduct());
+
+            Workbook workbook = new Workbook();
+            workbook.Worksheets.Add(); // Sheet1 
+            Worksheet worksheet = workbook.Worksheets[0];
+            worksheet.Cells[ 0,0].SetValue("=SUMPRODUCT({ 1,2,3}, { 4,5,6})"); //A1=32
+            CellSelection cell = worksheet.Cells[0, 0];
+            ICellValue cellValue = cell.GetValue().Value;
+            CellValueFormat cellFormat = cell.GetFormat().Value;
+            string formattedValue = cellValue.GetResultValueAsString(cellFormat);
+            Debug.WriteLine(formattedValue);
+
+
+            string fileName = "SampleFile.xlsx";
+            System.IO.File.Delete(fileName);
+            Telerik.Windows.Documents.Spreadsheet.FormatProviders.IWorkbookFormatProvider formatProvider = new Telerik.Windows.Documents.Spreadsheet.FormatProviders.OpenXml.Xlsx.XlsxFormatProvider();
+
+            using (Stream output = new FileStream(fileName, FileMode.Create))
+            {
+                formatProvider.Export(workbook, output, TimeSpan.FromSeconds(10));
+            }
+            Process.Start(new ProcessStartInfo() { FileName = fileName, UseShellExecute = true });
+        }
+    }
+
+    public class SumProduct : FunctionWithArguments
+    {
+        private static readonly string _name = "SUMPRODUCT";
+        private static readonly FunctionInfo _info;
+
+        static SumProduct()
+        {
+            string description = "The SUMPRODUCT function returns the sum of the products of corresponding ranges or arrays.";
+            string descriptionLocalizationKey = "Spreadsheet_Functions_SumProduct_Info";
+            IEnumerable<ArgumentInfo> requiredArguments = new ArgumentInfo[]
+            {
+            new ArgumentInfo("Array1", "The first array argument whose components you want to multiply and then add.", ArgumentType.Array, isRequired: true, "Spreadsheet_Functions_Args_Array", "Spreadsheet_Functions_SumProduct_Array"),
+            };
+
+            IEnumerable<ArgumentInfo> optionalArguments = new ArgumentInfo[]
+            {
+            new ArgumentInfo("ArrayX", "The array argument whose components you want to multiply and then add.", ArgumentType.Array, isRequired: true, "Spreadsheet_Functions_Args_Array", "Spreadsheet_Functions_SumProduct_Array"),
+            };
+
+            _info = new FunctionInfo(_name, FunctionCategory.Statistical, description, requiredArguments, optionalArguments, 254, false, descriptionLocalizationKey);
+        }
+
+        public override string Name => _name;
+
+        public override FunctionInfo FunctionInfo => _info;
+
+        protected override RadExpression EvaluateOverride(FunctionEvaluationContext<object> context)
+        {
+            double result = 0;
+            try
+            {
+                List<ArrayExpression> arrayExpressions = new List<ArrayExpression>();
+                foreach (ArrayExpression array in context.Arguments)
+                {
+                    arrayExpressions.Add(array);
+                }
+
+                int nbElements = arrayExpressions.First().Count();
+                if (!arrayExpressions.Any(a => a.Count() != nbElements))
+                {
+                    List<double> values = new List<double>(nbElements);
+                    for (int i = 0; i < nbElements; i++)
+                    {
+                        values.Add(1);
+                    }
+
+                    for (int i = 0; i < values.Count; i++)
+                    {
+                        for (int j = 0; j < arrayExpressions.Count; j++)
+                        {
+                            string value = arrayExpressions[j].Value.ElementAt(i).ToString();
+                            if (double.TryParse(value, out double doubleValue))
+                            {
+                                values[i] *= doubleValue;
+                            }
+                            else
+                            {
+                                values[i] = 0;
+                            }
+                        }
+                    }
+
+                    result = values.Sum();
+                }
+            }
+            catch
+            {
+                // Do nothing
+            }
+
+            return new NumberExpression(result);
+        }
+    }
+```
+
+
+Avoid using nested array formulas inside the spreadsheet. Instead, preprocess arrays in your code and provide numeric arrays as direct input to the custom function.
+
+## See Also
+
+- [Telerik Document Processing](https://docs.telerik.com/devtools/document-processing/introduction)
+- [SpreadProcessing: Implement the SUMPRODUCT Function](https://feedback.telerik.com/document-processing/1625149-spreadprocessing-implement-the-sumproduct-function)
+- [SUMPRODUCT Function in Excel](https://support.microsoft.com/en-us/office/sumproduct-function-16753e75-9f68-4874-94ac-4d2145a2fd2e)