Date: Jun 16, 2013 5:14 AM
Author: Murray Eisenberg
Subject: Re: Multiplication by 0: non-zero in versions 8 and 9

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@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@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