Stephen J. Herschkorn wrote:
fred wrote:

Do any of you SCI.MATH whizes want to weigh in on this?

MS Excel calculates "=-5^2" as 25, not as -25.
This is because 'negation' is handled first in Excel. (!?)
If you put a zero in the equation,
as in "=0-5^2", your answer changes to -25.

Is this in line with standard math rules?
Is negation different than subtraction?

I'm getting a lot of comments in the Excel NG
basically saying that "it's in the help section, so too bad".

I've had lots of math and as far as I know
negation and subtraction are the same thing.


Alan Beban wrote:

Well, this is an Excel forum, so one should expect a programming point
of view. But if you search on mathematical notation generally, I
think negation is viewed as a unary operator, while subtraction is
viewed as a binary operator; and the discussions are not much clearer
in that context. My own view, not as a mathematician, is that the
issue revolving around how to evaluate -1^2 depends on some *order of
precedence*, and is totally conventional as to negation and
exponientation.




BOULDERDASH!!! This is a horrible bug in Excel (whereof I was
previously unaware). It is very standard that exponentiaion takes
precedence over negation. Ask any semi-decent high school student to
draw a graph of y = -x^2, and what will you get?

Stating it is a documented convention is not a legitimate argument.
What if Microsoft(R) buried in its documentation that addition takes
precedence over multiplication? That the spell checker would always
change word "friend" to "freind"? That the sum function adds only every
other term? That using a "q" in one of its products would cause the
system to reboot? These effects would be just as valid by this logic.

I have sent this comment to Microsoft(R), though I expect no good to
come of it.


Pounding on the desk about it being "very standard that exponientation
takes precedence over negation" is much less persuasive than would be
citing the "standard" order of precedence rules applicable in
mathematics. I don't find what "a semi-decent high school student" would
do to be very compelling. Why can't the people who are so emotional
about the issue (which, incidentally, seems to have been resolved in C
the same way as it is in Excel, which is hard to blame Microsoft for)
cite some persuasive authority besides the fact that their grandmother
taught them to Please Excuse My Dear Aunt Sally, which my limited Google
search suggests is applicable to only the binary operators listed and
not to unary operators? Maybe we could all learn something if we were
directed to an authoritative source of the convention in ordinary
mathematics without regard to programming.

Alan Beban