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Re: How to look for this kind of error

  • To: mathgroup at smc.vnet.net
  • Subject: [mg124561] Re: How to look for this kind of error
  • From: DrMajorBob <btreat1 at austin.rr.com>
  • Date: Wed, 25 Jan 2012 07:00:24 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <201201241008.FAA20312@smc.vnet.net>
  • Reply-to: drmajorbob at yahoo.com

Even without Simplify or FullSimplify, Mathematica frequently makes  
assumptions that don't hold in individual cases.

A trivial case is

x/x

1

which is wrong for x == 0.

Your expressions probably involve a more complicated form of the very same  
cancellation.

Bobby

On Tue, 24 Jan 2012 04:08:48 -0600, Sam Takoy <sam.takoy at yahoo.com> wrote:

> Hi,
>
> Suppose I have a very complicated function TestCodazzi and
>
> TestCodazzi[0,2,3]
>
> returns one answer while
>
> TestCodazzi[0, x, y] //FullSimplify /. {x->2, y->3}
>
> returns a totally different answer. Now, there is a lot going on and I
> could start testing different parts of my code. However, could
> Mathematica show me the instances where it was making certain
> assumptions that may not be true, and so help me in tracking down this
> discrepancy?
>
> Many thanks in advance,
>
> Sam
>


-- 
DrMajorBob at yahoo.com



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