I think Omitting the multiplication sign is a big mistake

[a boy]

In philosophical sense, to omit the multiplication sign is incorrect.
Space-key or null is always describe the place of objects.
A little student may think a(b+c)=ab+ac ==> 2(3+4)=23+24 ?
In Mathematica, array[[n]] puzzled almost all of new ones who never
used the software.

[Murray Eisenberg]

That's a wonderful example illustrating the difficulties of traditional
mathematical notation, the sort of thing that makes one appreciate why
so many students don't understand it. The fact that traditional math
notation was designed to handle single-letter variables with aplomb
makes thing even more confusing when students have to deal with
multi-character variables.

A couple of programming languages have built on, among other things, the
principle that every operation must be explicitly indicated with a
symbol (so no space and no juxtaposition to denote multiplication). Such
of those languages that I know (APL and J) also abandon any hierarchy of
operators of the same kind, e.g., no precedence of multiplication over
addition (but they impose a different kind of precedence among
"functions" and "operators" or, as Ken Iverson later preferred to call
them, "verbs" and "adverbs" and "conjunctions").

--
Murray Eisenberg mur...@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

[David Bailey]

On 14/07/2011 10:21, Murray Eisenberg wrote:
> That's a wonderful example illustrating the difficulties of traditional
> mathematical notation, the sort of thing that makes one appreciate why
> so many students don't understand it. The fact that traditional math
> notation was designed to handle single-letter variables with aplomb
> makes thing even more confusing when students have to deal with
> multi-character variables.
>
> A couple of programming languages have built on, among other things, the
> principle that every operation must be explicitly indicated with a
> symbol (so no space and no juxtaposition to denote multiplication). Such
> of those languages that I know (APL and J) also abandon any hierarchy of
> operators of the same kind, e.g., no precedence of multiplication over
> addition (but they impose a different kind of precedence among
> "functions" and "operators" or, as Ken Iverson later preferred to call
> them, "verbs" and "adverbs" and "conjunctions").
>
>
> On 7/13/11 3:11 AM, a boy wrote:
>> In philosophical sense, to omit the multiplication sign is incorrect.
>> Space-key or null is always describe the place of objects.
>> A little student may think a(b+c)=ab+ac ==> 2(3+4)=23+24 ?
>> In Mathematica, array[[n]] puzzled almost all of new ones who never
>> used the software.
>>
>

Of course, you have to work quite hard using HoldForm to actually output
the expression 2 3 + 2 4,so the problem is with input where two numbers
are adjacent. I think an optional syntax restriction to require a "*"
between two numbers, or else an error, might be quite useful.

David Bailey
http://www.dbaileyconsultancy.co.uk

[Murray Eisenberg]

With current versions of Mathematica, of course, you get a
multiplication sign between adjacent numbers by default. And it's a
"real" multiplication sign -- the kind that looks like an x (no serifs)
-- and not the computerese * symbol.

--

[David Bailey]

On 15/07/2011 09:09, Murray Eisenberg wrote:
> With current versions of Mathematica, of course, you get a
> multiplication sign between adjacent numbers by default. And it's a
> "real" multiplication sign -- the kind that looks like an x (no serifs)
> -- and not the computerese * symbol.
>

I don't see that explicit multiplication sign - certainly not on the
default notebook that opens when you start Mathematica. However, I know
I have seen it somewhere - do you know how to turn it on?

David Bailey
http://www.dbaileyconsultancy.co.uk

[Murray Eisenberg]

I thought it was now the default -- but only for actual numbers, not
symbols.

The relevant option is:

Formatting Options > Expression Formatting > Display Options
> AutoMultiplicationSymbol

--

[Gary Owen]

Edit=>Preferences=>Appearance=>Numbers=>Multiplication. Check the
box beside 'Automatically display multiplication symbol between
multiplied numbers'.

[Bill Rowe]

On 7/18/11 at 6:14 AM, da...@removedbailey.co.uk (David Bailey) wrote:

>On 15/07/2011 09:09, Murray Eisenberg wrote:
>>With current versions of Mathematica, of course, you get a
>>multiplication sign between adjacent numbers by default. And it's a
>>"real" multiplication sign -- the kind that looks like an x (no
>>serifs) -- and not the computerese * symbol.

>I don't see that explicit multiplication sign - certainly not on the
>default notebook that opens when you start Mathematica. However, I
>know I have seen it somewhere - do you know how to turn it on?

In the MacOS X FrontEnd, you can change this behavior by doing
cmd-, to bring up the preferences dialog. Then within that
select the Appearance tab and next the Multiplication sub-tab.
There you will find a check box that enables/disables the
automatic multiplication display as well as a menu item that
gives you a choice of how this automatic display is to be done.
I assume there is an analog to the steps above for other
operating systems.

[Vince Virgilio]

If I understand the question . . . .

In Mathematica 8: Edit > Preferences > Appearance > Numbers > Multiplication

Vince Virgilio

[Helen Read]

Edit, Preferences -> Appearance -> Numbers -> Multiplication

Checkbox "Automatically display multiplication symbol between multiplied
numbers"
dropdown offers choice of symbols.

--
Helen Read
University of Vermont