Automatically fill in results tables

Thanks for that, I went with the latter.

I tried to use the same principle with E column,

=IF(H37="","",IF(H37="M",$E$1/D37,$E$2/D37))

so I now get blanks, but this hasn't solved the problem with P and X column array formula results.

I get the impression I'm missing something very simple with this that would get it to work.