var spread =
new GC.Spread.Sheets.Workbook(document.getElementById('ss'),
{ sheetCount: 1 });
sheet = spread.getSheet(0);
sheet.setValue(0, 0, 1);
sheet.setValue(1, 0, 2);

// Using EvaluateFormula() method to evaluate formula without setting formula in sheet's cell
var result =
GC.Spread.Sheets.CalcEngine.evaluateFormula(sheet, "SUM(A1:A2)", 0, 0);
console.log("SUM(A1:A2) = " + result);