The late, great Bob Pease was fond of pointing out
that both SPICE
 and spreadsheets are great at giving you the answer you want, not the
 answer you need (the right one). 
There's a bit of doggerel which I saw presented as coming from a
graffito in a terminal room (back when there _were_ terminal rooms, of
course):
        I really hate this damn machine
        I wish that they would sell it
        It never does quite what I want
        But only what I tell it
Computers are really good at answering the question you asked, not the
question you meant to ask - or the question you thought you asked - or
the question you actually need the answer to....
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