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MathGroup Archive 2007

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Re: Re: Re: RE: Re: Sometimes <space> means multiple

  • To: mathgroup at smc.vnet.net
  • Subject: [mg75442] Re: [mg75426] Re: [mg75423] Re: [mg75364] RE: [mg75358] Re: Sometimes <space> means multiple
  • From: János <janos.lobb at yale.edu>
  • Date: Tue, 1 May 2007 03:19:55 -0400 (EDT)
  • References: <200704270918.FAA23598@smc.vnet.net> <200704290714.DAA21234@smc.vnet.net> <200704300738.DAA22373@smc.vnet.net>

I think the reason for "space" used as multiply is the typical anglo-
american intellectual laziness :)  /Old Hungarian proverb:  "Whose 
shirt it is not, should not take it on"/

Steve just did not want to type an extra character when he came up 
with the design - that is it.  He was also constrained by the ASCII 7 =

bit.

If I look back on my education for multiplication in elementary 
school a dot was use on the "middle of the lane".  On a Mac it is 
<Option>+<Shift>+<9>.

Now to use that would have been more painful than just <Shift>+<8>, 
wouldn't it ?.

The <Shift>+<8> came to the math circles via computers and with punch =

cards where the restrictive ASCII 7 bit ruled the world and "a" and 
"b" had to be tightened with SOMETHING.

Looking many professional journal pdfs one thing is sure.  Neither 
the "space" nor the "star" is used for multiplication.  It is still 
the dot on the "middle of the lane", a small "x" or nothing.  That 
is, I never see "a*b" or "a b" as a multiplication of a and b but 
rather I see "ab" or "a=B7b".

With the best,

J=E1nos
P.S.  If I take the "a b" to its ultimate test and "try" it in pre-
fix " ab" or post-fix "ab " that shows clearly the dumbness of the 
usage of space in its pure naked form :)

On Apr 30, 2007, at 3:38 AM, Andrzej Kozlowski wrote:

> I compltely agree. I also think that any comparisons between C++ and
> Mathematica in this respect are completely off the mark, unless of
> course sombody decides to develop an analogue of "TradtitionalForm"
> for C++.
>
> I would also like to point out the following obvious but not
> insignificant fact. Enter  a b (or 2 3  if you prefer) and convert to
> InputForm. You will obtain an explicit asterisk in place of the
> space. Conversely, enter a*b and convert to TraditionalForm (or even
> StandardForm). You will get a space instead of the asterisk. This, in
> my opinion,  is exactly how it should be. In fact, I am somewhat
> shocked that anyone would claim otherwise.
>
> Andrzej Kozlowski
>
>
> On 29 Apr 2007, at 16:14, Murray Eisenberg wrote:
>
>> Why "mistake"?  Why not allow Mathematica to mimic as much of
>> traditional mathematical notation as possible without running into
>> genuine ambiguity?
>>
>> After all, it's really convenient to be able to use 2 Exp[x] and 
>> Cos[2
>> t] -- and even 2Exp[x] and Cos[2t] -- without having to insert an
>> extra,
>> distracting multiplication symbol.  Then the usage in 2 4, for
>> example,
>> just extends that.
>>
>> In my own work, I ordinarily include an explicit multiplication 
>> symbol
>> -- and I prefer the multiplication sign one gets from Esc * Esc 
>> instead
>> of the FORTRANish * -- when the factors are numbers.  There's
>> nothing to
>> prevent you from doing that if you don't like the implicit
>> multiplication indicated by a space.
>>
>>
>> Virgilio, Vincent - SSD wrote:
>>> Personally, I think it was a mistake to overload the meaning of
>>> "space"
>>> to multiply. I bet Wolfram Inc. would reverse that decision now,
>>> if it
>>> wasn't for backward compatibility.
>>>
>>> I like to compare Mathematica to C++. Somewhere in his writings,
>>> Bjarne
>>> Stroustrup mentions the same issue, and his decision not to overload
>>> whitespace. I think the question also arises on the Boost mailing
>>> lists
>>> now and then, mostly tongue-in-cheek.
>>>
>>> (Corrections welcome.)
>>>
>>> Vince Virgilio
>>>
>>> -----Original Message-----
>>> From: Bill Rowe [mailto:readnewsciv at sbcglobal.net]
>>> Sent: Thursday, April 26, 2007 3:35 AM
>>> To: mathgroup at smc.vnet.net
>>> Subject: [mg75364] [mg75358] Re: Sometimes <space> means
>>> multiple , sometimes not
>>>
>>> On 4/25/07 at 5:27 AM, siewsk at bp.com wrote:
>>>
>>>> As a newbie, I was taught that <space> character in Mathematica
>>>> means
>>>> multiple. But sometimes it does not.
>>>
>>>> For example:
>>>
>>> <examples snipped>
>>>
>>> Mathematica allows spaces to be placed before or after any 
>>> operation.
>>> Consequently, a space is only interpreted as a multiply when there
>>> is no
>>> other operator or other possible interpretation.
>>>
>>> So, -4 -2 is the same as -4 - 2 or -4-2 and gives -6 but
>>>      -4 (-2) will yield 8
>>> --
>>> To reply via email subtract one hundred and four
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>>
>> --
>> Murray Eisenberg                     murray at math.umass.edu
>> Mathematics & Statistics Dept.
>> Lederle Graduate Research Tower      phone 413 549-1020 (H)
>> University of Massachusetts                413 545-2859 (W)
>> 710 North Pleasant Street            fax   413 545-1801
>> Amherst, MA 01003-9305
>>
>



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