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Re: Multiplication by 0: non-zero in versions 8 and 9

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  • Subject: [mg131195] Re: Multiplication by 0: non-zero in versions 8 and 9
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Sun, 16 Jun 2013 05:20:55 -0400 (EDT)
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In fact, the Mathematica behavior you observe in later versions, while 
possibly disconcerting on strictly mathematical grounds, is reassuring 
on software consistency grounds. Thus, the 9.0.1 documentation page 
tutorial/ExactAndApproximateResults says:

  "Whenever you give a number with an explicit decimal point, 
Mathematica produces an approximate
   numerical result [for a calculation involving that number]."

Personally, I would be unhappy if I did a calculation some of whose 
numbers were approximate yet whose answer gave a misleading exact 
answer.
On Jun 15, 2013, at 4:23 AM, Sotirios Bonanos 
<sbonano at inp.demokritos.gr> wrote:

> Hello ,
>
> I have noticed that in all Mathematica versions <8, multiplying a real 
or complex number by the integer 0 gives 0, but in versions 8 and 9
>
> Times[0, 0.567] gives 0.
>
> and
>
> Times[1.23 + I 2.45, 0] gives 0. + 0. I
>
> I don't know what prompted this change but it is definitely wrong: the 
zero property of multiplication holds for real and complex numbers also 
(see https://en.wikipedia.org/wiki/Multiplication#Properties) .
>
> Sotirios Bonanos
> http://www.inp.demokritos.gr/~sbonano/
>

---
Murray Eisenberg                                    
murray at math.umass.edu
Mathematics & Statistics Dept.      
Lederle Graduate Research Tower            phone 413 549-1020 (H)
University of Massachusetts                               413 545-2838 (W)
710 North Pleasant Street                         fax   413 545-1801
Amherst, MA 01003-9305








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