Hi, I saw this formula
Formula: copy to clipboard 
=SUMPRODUCT(--(A1>{0,1000000,5000000}),A1-{0,1000000,5000000},{0.01,-0.003,-0.001})


It's basically calculating this:
1,000,000 at 1.00% = 10,000
4,000,000 at 0.70% = 28,000
3,000,000 at 0.60% = 18,000

I don't understand though what the -- is there for.

Also, could someone take me through the steps of what it's actually doing? I get the broad logic, but just want a bit of clarity as to how it is working.

Any explanation would be great.

Thanks