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Re: [Phys-L] math notation puzzles



Okay, I'll be the patsy. For the first two, my best bet would be -9. Exponentiation generally takes precedence over negation. However, a writer of an interpreter or compiler can do it any way they want; there are probably some for which the result is 9. There might be some that introduce a rounding error. My TI83+ calculator gives -9. Microsoft Excel gives 9. I'm not sure at all of my answer. When in doubt, I use parentheses, or, in some cases, I experiment to find out how the device/language I am working with handles the expression.

For the third one, I'm going to give an answer that is valid for one set of assumptions, namely, that the dot operator is the symbol being used for ordinary multiplication of scalars, the kind of multiplication we learned in elementary school, and the plus operator is the symbol being used for ordinary addition of scalars, the kind we learned in elementary school. Furthermore, I am assuming that the expression is to be interpreted using the rules for the algebra that we learned in middle school. Under those assumptions, I am certain that the expression evaluates to 25 to with a precision consistent with the precision to which the given values are known.

-----Original Message-----
From: Phys-l <phys-l-bounces@mail.phys-l.org> On Behalf Of John Denker
via Phys-l
Sent: Tuesday, February 5, 2019 6:05 PM
To: Phys-L@Phys-L.org
Cc: John Denker <jsd@av8n.com>
Subject: [Phys-L] math notation puzzles

Some puzzle questions:

1) Some computer languages use ^ as the exponentiation operator. In that
case, what is the numerical value of:
-3​^​2

How do you know?
How sure are you?

2) Some computer languages use ** as the exponentiation operator. In that
case, what is the numerical value of:
-3**2

How do you know?
How sure are you?

3) What is the numerical value of:
3⋅3 + 4⋅4

How do you know?
How sure are you?


==============
For each question:

-- I have an answer in mind.
-- I expect that after the dust settles, there will be near-universal agreement
as to the right answer.
-- There is a reason for asking the question.
-- I have not done anything to make it trickier than it needs to be.
-- You are warned that the question might not be as easy as it initially
appears. That is to say, there is a certain amount of irreducible trickiness.

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