Speeding up the insertion of formulas via xlcFormula via Excel-DNA

Question

I am using Excel-DNA to insert formulas into about 40k rows * 10 columns, and it is quite slow.

 XlCall.Excel(XlCall.xlcFormula, myFormula, new ExcelReference(row, row, column, column));

I managed to improve it dramatically by temporarily disabling the recalculation of cells on update (XlCall.Excel(XlCall.xlcCalculation, 3);), but ideally I would like to find a way to put an entire column of formulas into excel in a single operation (I am assuming this would improve the speed).

I tried passing an object[,] with my call to xlcFormula:

 XlCall.Excel(XlCall.xlcFormula, excelFormulas, new ExcelReference(1, lastRow, columnNumber, columnNumber));

but it put all the formulas into a single field (separated by semicolons). Is there a way to do what I am trying to do, or am I wasting my time on something that is impossible?

Answer 1

You could try it with screen updating also switched off XlCall.Excel(XlCall.xlcEcho, false).

What about using the Clipboard? You could copy the formulae (with tabs between the columns) to the clipboard, and paste all at once into the Excel sheet. This would probably be as fast as you could get Excel to process the formula strings.

Answer 2

I also had this trouble and figured out another way to speedup formula insertion. Try this code:

var formula = "=1+2";
var reference = new ExcelReference(rowFirst, rowLast, columnFirst, columnLast); // it's а rectangular area, just split up your huge area to smaler ones here
XlCall.Excel(XlCall.xlcFormulaFill, new object[] { formula, reference } ));

This code is good when you want to insert the same formula into a lot of cells. Try to use relative references in the formula.

Previous solution also works:

XlCall.Excel(XlCall.xlcEcho, false)

... but don't forget to enable echo from time to time.