       LeafCount Question

• To: mathgroup at smc.vnet.net
• Subject: [mg25782] LeafCount Question
• From: "Dana" <dana_news at hotmail.com>
• Date: Wed, 25 Oct 2000 03:53:42 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

```Hello.  Using Mathematica 4.0  When one solves equations, I get a little frustrated
when the answers come out as
-A +B, when the answer looks much better as...
B - A

I was hoping that the "LeafCount" would be smaller with my "preferred" way,
but for some reason, it does not look like there is a difference.

In:=
{LeafCount[-B + D], LeafCount[D - B]}

Out=
{5, 5}

Here is a simple Solve, and it is a little embarrassing to say the answer is
(-B + D)..Etc when  everyone else will have to change this  manually to (D -
B)...ect.

Is there a way around this?  Again, I was hoping LeafCount would do the
trick, but it apparently does not.

FullSimplify[Solve[{Y == A*X + B, Y == C*X + D}, {X, Y}],
ComplexityFunction -> LeafCount]

{{X -> (-B + D)/(A - C), Y -> (-(B*C) + A*D)/(A - C)}}

Since I am new to Mathematica, I noticed the following...
Internally, it looks like no difference.  It is just frustrating.

In:=
{FullForm[(-B + D)], FullForm[(D - B)]}

Out=
{Plus[Times[-1, B], D], Plus[Times[-1, B], D]}

```

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