Hi Jon
This bit:
Code:
SUMIF(I4:I20,{"Core","Existing"},G4)
Gives a horizontal array of 2 totals, one has the SUM of all the "Core"s, the other has the SUM of all the "Existing"s. So something like {5,10}
Then SUM() adds them together to give 15.
Since {"Core","Existing"} is an inline array constant (ie. containing directly within the formula), the formula does not have to be CSE entered. (My definition would be that this is already an "Array Formula".)
Conversely, if you were to use a named array constant, MyArray, where MyArray is defined as:
Code:
MyArray ={"Core","Existing"}
Then this formula would have to be CSE entered, I think because 'MyArray' is like a pointer to the names table, you have to tell Excel to treat it like an array:
Code:
=SUM(SUMIF(I4:I20,MyArray,G4)) 'CSE entered
'or
=SUMPRODUCT(SUMIF(I4:I20,MyArray,G4))
So then comes the $1M question... which formula is best here? My guess would be Andrew's =SUMIF(I4:I20,"Core",G4:G20)+SUMIF(I4:I20,"Existing",G4:G20). But if lots of conditions then it becomes unwieldly - I've not tested efficiency between yours and mine, I suspect =SUMPRODUCT((I4:I20="core")+(I4:I20="existing"),G4:G20) might just edge it, but I'm not sure without running some tests. One of the formula experts here will know.
HTH
Colin