User-defined function to split a 1D array into 2D array
"receive a 1D array and split it into a 2D array" - it's not true, it receives a 2d array of which 2nd dimension is 1. It won't work receiving an 1D or transposed 2D array. (it probably serves your purpose, just be clear with the description to avoid confusion in the future.



If ArraySize Mod MaxRow &gt; 0 Then MaxCols = MaxCols + 1


Although this is correct syntax it's generally a bad practice to write IF in one line.



You can simplify your calculations:

y = x Mod MaxRow
If y = 0 Then y = MaxRow


=> y = ( (x - 1) Mod MaxRow) + 1

z = x \ MaxRow
If x Mod MaxRow = 0 Then z = z - 1


=> z = (x-1) \ MaxRow

(These will not work correctly for 0 index, however in your case arrays copied from Range always have index starting from 1.