If your main concern is speed = efficiency look again at Tushar's answer.
moving data into an array / working /and writing back is almost always
faster than mechanically doing things in "Excel proper".

"Josh Sale" wrote:

I'm looking for an efficient way to set the formulas on a range of cells.

My situation is that I have a VBA array that contains one formula in R1C1
format for each cell of the array. Some of the cells in the array contain
empty strings indicating that the corresponding cell has no formula.

If is use code like:

myRange.FormulaR1C1 = myFormulaArray

Then the cells associated with elements of the array that contain empty
strings lose their value ... and I want to preserve the values in those
cells.

Right now, I'm using two nested loops to iterate through myFormulaArray
looking for non-empty strings and then setting the formula's a cell at a
time. It works but is slow as the array grows in size.

I've looked at the FormulaArray property and its description looks
tantalizingly like what I'm looking for. But it doesn't seem to work either
.... but maybe I'm doing something wrong here since I don't really understand
what a FormulaArray is.

Anybody got any suggestions?

TIA,

josh

p.s. Ideally the solution would work on XL97 and later ... but I could live
with a solution that only worked with later versions of Excel.