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Re: broadcasting of Equal ? (newbie question)

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This indeed seems to be an oversight in the reference page for Solve. 
Perhaps due to the fact that Threading Equal over lists -- which, 
technically, is what Solve is doing -- came relatively late to 
Mathematica (version 5?).

Definitely something worth reporting to Wolfram Research as a suggestion.

There actually is something about this in the documentation, but in a 
different place: tutorial/SimultaneousEquations. About 2/3 or 3/4 down 
the page there you'll find a box with caption "Ways to present 
simultaneous equations to Solve". The third of the three ways listed 
there is with a list on the left of == and a corresponding list on the 
right. And just one example:

   {{3, 1}, {2, -5}}.{x, y} == {7, 8}

   Solve[%, {x, y}]

To my mind, that example is not optimal in that it ought to be put 
directly, or eventually, in the form:

   Solve[ {{3, 1}, {2, -5}}.{x, y} == {7, 8}, {x, y}]

Or perhaps even more directly in the form:

   Solve[{3x + y, x - 5y} == {7, 8}, {x, y}]

And, in any case, mention and example of such implicit Threading should 
go on the reference page for Solve, too.


On 4/14/2011 4:49 AM, Alan wrote:
> I noticed that e.g.
> Solve[{x + y - 1, 2 x + y - 2} == {0, 0}, {x, y}]
> can be written as
> Solve[{x + y - 1, 2 x + y - 2} == 0, {x, y}]
> but I cannot find the rule that allows this.
> (E.g., I do not find it in the help for Equal
> or the help for Solve.)
>
> Can you point me to it?
>
> Thanks,
> Alan
>

-- 
Murray Eisenberg                     murray@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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Re: broadcasting of Equal ? (newbie question) Murray Eisenberg <murray@math.umass.edu> - 2011-04-15 07:55 +0000

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