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MathGroup Archive 2007

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Re: Sometimes <space> means multiple , sometimes not

  • To: mathgroup at smc.vnet.net
  • Subject: [mg75348] Re: [mg75307] Sometimes <space> means multiple , sometimes not
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Thu, 26 Apr 2007 03:29:34 -0400 (EDT)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <200704250927.FAA25904@smc.vnet.net>
  • Reply-to: murray at math.umass.edu

What's the problem?  Every mathematician "knows" what each of the 
expressions below is supposed to mean, and they know they mean exactly 
what Mathematical is telling you they mean.

The usual mathematical conventions are being followed here, which use a 
hierarchy specifying an order of precedence.


Traditional mathematical notation is a real mess: it's a wonder anybody 
ever learns it.  If you want a rational, consistent notation, use APL or J!

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:
> 
> 4<space>2  gives 8
> 
> but
> 
> -4<space>-2 does not give -8
> 
> This strange behavior can be show below
> 
> In[1]:= 4 2   (* 4<space>2 *)
> Out[1]= 8
> 
> In[2]:= 4 +2   (* 4<space>+2 *)
> Out[2]= 6
> 
> In[3]:= +4 2   (* +4<space>2 *)
> Out[3]= 8
> 
> In[4]:= +4 +2   (* +4<space>+2 *)
> Out[4]= 6
> 
> In[5]:= +4 -2  (* +4<space>-2 *)
> Out[5]= 2
> 
> In[6]:= 4 -2   (* 4<space>-2 *)
> Out[6]= 2
> 
> In[7]:= -4 -2  (* -4<space>-2 *)
> Out[7]= -6
> 
> In[8]:= -4 2  (* -4<space>2 *)
> Out[8]= -8
> 
> 

-- 
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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