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Re: What does & mean?

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  • Subject: [mg107081] Re: What does & mean?
  • From: Bill Rowe <readnews at>
  • Date: Tue, 2 Feb 2010 03:28:36 -0500 (EST)

On 2/1/10 at 6:14 AM, micknudsen at (Michael Knudsen) wrote:

>I have recently bought Mathematica, and I have a really tough time
>getting started. I'm reading the various documents found under
>"Complete Documentation" at the Mathematica homepage, but it doesn't
>feel like the right place to start.

>For example, I'm now trying to solve some simple differential
>equations, and the documentation provides the following example:

>A = {{4, -6}, {1,-1}};

>X[t_] = {x[t], y[t]}; system = MapThread[#1 == #2 &, {X'[t],

>sol = DSolve[system, {x,y}, t]

>However, there is no explanation of how & works here (and it isn't
>in the MapThread documentation either). Where should one start
>reading in order to understand basic constructs like this? This
>particular example is really nasty, since & is generally ignored by
>search engines.

The "&" character is used here to define a pure function. In
this case, the pure function equates the two arguments given to
it. More information on how "&" works can be found by searching
on either the character "&" or Function in the Documentation
Center. At the bottom of the documentation page is a set of
links to tutorials with more information.

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