       Re: Just another Mathematica "Gotcha"

• To: mathgroup at smc.vnet.net
• Subject: [mg120832] Re: Just another Mathematica "Gotcha"
• From: DrMajorBob <btreat1 at austin.rr.com>
• Date: Fri, 12 Aug 2011 05:04:50 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• References: <201108110912.FAA07274@smc.vnet.net>

```That's not what operator precedence means, at all.

Put the original expression:

Series[a + (b1 + b2) x, {x, 0, 1}] // Normal /. {b2 -> 0}

into Mathematica and

1) triple-click on /. and watch the selection become Normal /. {b -> 0}.
(If you quadruple-click, you get the entire statement.)

2) triple-click on // and the selection expands to the whole statement.

Hence, /. binds its arguments (Normal and the replacement rule) first,
then // binds its arguments (Series and Normal).

Bobby

On Thu, 11 Aug 2011 04:12:41 -0500, Glenn Carlson <g.crlsn at gmail.com>
wrote:

> It seems not simply a matter of operator precedence since  evaluates
> to neither  nor .
>
> In:= Series[a + (b1 + b2) x, {x, 0, 1}];
> % // Normal;
> % /. {b2 -> 0}
>
> Out:= a+b1 x
>
> In:= Series[a + (b1 + b2) x, {x, 0, 1}];
> % /. {b2 -> 0};
> % // Normal
>
> Out:= a+b1 x
>
> In:= Series[a + (b1 + b2) x, {x, 0, 1}] // Normal /. {b2 -> 0}
>
> Out:= a + (b1+b2) x
>

--
DrMajorBob at yahoo.com

```

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