       Re: What does & mean?

• To: mathgroup at smc.vnet.net
• Subject: [mg107074] Re: [mg107050] What does & mean?
• From: cire g <eric.phys at gmail.com>
• Date: Tue, 2 Feb 2010 03:27:20 -0500 (EST)
• References: <201002011114.GAA22737@smc.vnet.net>

```I have the same problem and I had been using Mathematica for a while,
for example can any one explain the code to color a sum:

f[X_List, m_Integer] := Module[{Y},
Y = Partition[X, m];
Z = MapThread[(c = If[OddQ@#2, Red, Blue];
Style[#, c, Bold, 18] & /@ #1) &, {Y, Range@Length@Y}];
Infix[Flatten@Z, Style["+", 18]]];

f[Table[1,{15}],3]

in the documentation is not a good explaining the use of @,#, & etc...
that make those codes very hard to decipher...

bests

Michael Knudsen wrote:
> Hi,
>
> 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], A.X[t]}];
>
> sol = DSolve[system, {x,y}, t]
>
> However, there is no explanation of how & works here (and it isn't in
> order to understand basic constructs like this? This particular
> example is really nasty, since & is generally ignored by search
> engines.
>
> Thanks,
> Michael Knudsen
>
>
>

```

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