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Re: Order of operations (was: Eigenvalues &/or eigenvectors, anyone?)
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Re: Order of operations (was: Eigenvalues &/or eigenvectors, anyone?)


  • Subject: Re: Order of operations (was: Eigenvalues &/or eigenvectors, anyone?)
  • From: Deivy Petrescu <email@hidden>
  • Date: Thu, 8 May 2003 12:42:35 -0400

On Thursday, May 8, 2003, at 11:25 AM, Doug McNutt wrote:

At 20:31 -0700 5/7/03, Michael Kelly wrote:
Wow. I am both horrified and intrigued. Is there an actual reason for
this, or did some bored Apple tech just decide to change the order of
operations to mess with people's minds?

I did file a bug report and it made it up the chain far enough to get a number. The problem is that some professor in some computer science department decided there was something called a "unary minus" operator which is not a subtraction. Back when algebra was taught in high school - remember that? - we learned that a leading minus sign implied a preceding zero.

Doug, I do not know if I can excuse you for that, so before I reply to you, let me say something on the side
<side note>
Chris,
I still have my grievances with some of the numerical stuff in AS
</side note>

AS is right and the other programs are all, if not wrong, using a not canonic notation.
-2^2=4 is what i know to be true. And even if you want to use your HS algebra, then
-2= 0-2
now let us square that:
(0-2)^2=4
unless you feel like just squaring them second term, like:
0-2^2 which is -4.

However, this second method is, really, not right!

If you have a calculator, it probably has a +/- key which allows you to change the sign of the number in the display.
This is different than the (-) key, which is used in case of a subtraction.
The first key is the "unary" "-" and the second is the usual "binary" subtraction.

I'm waiting for a bridge to fall down because engineers aren't computer-science savvy. But then statics can involve eigenvectors so it's not likely to be the fault of AppleScript.

Something like this already happened at NASA! They mixed units, British and SI. I can not remember what was it, but it was major...
I do not believe it was AS fault.

Larry Wall briefly discusses the subject in "Programming Perl", O'Reilly, ISBN 0-596-00027-8, page 92.

--

Have not seen the book, I can not comment, however, kudos here for the AS people because they got it right.
(please see side notes above, please) 8)


--> There are 10 kinds of people: those who understand binary, and those who don't <--
_______________________________________________


I like that!


Regards

Deivy Petrescu
http://www.dicas.com/
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  • Follow-Ups:
    • Re: Order of operations (was: Eigenvalues &/or eigenvectors, anyone?)
      • From: Doug McNutt <email@hidden>
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 >Re: Order of operations (was: Eigenvalues &/or eigenvectors, anyone?) (From: Doug McNutt <email@hidden>)

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