Re: Bug in NMinimize?
- To: mathgroup at smc.vnet.net
- Subject: [mg108472] Re: Bug in NMinimize?
- From: Brett Champion <brettc at wolfram.com>
- Date: Fri, 19 Mar 2010 02:48:06 -0500 (EST)
On Mar 18, 2010, at 4:34 AM, Andrzej Kozlowski wrote:
> Hi Janos,
>
> You are being really unkind to Mathematica here ;-). You are asking
> her to
> solve an impossible problem and when it can't do it you denounce it
> to the
> world... Actually, it will tell you what the problem is if you
> specify any
> of the possible Method options explicitly, for example:
>
> NMinimize[{1,x+y>==1,2 x+2 y<==0,Element[x,Integers]},{x,y},Method-
> >"DifferentialEvolution"]
>
> During evaluation of In[24]:== NMinimize::incst: NMinimize was
> unable to generate any initial points satisfying the inequality
> constraints {-y-Round[x]+1<==0,2 y+2 Round[x]<==0}. The initial
> region specified may not contain any feasible points. Changing the
> initial region or specifying explicit initial points may provide a
> better solution. >>
> During evaluation of In[24]:== NMinimize::nosat: Obtained solution
> does not satisfy the following constraints within Tolerance ->
> 0.001: {-x-y+1<==0,2x+2 y<==0}. >>
> {1.,{x->0,y->0.2}}
>
> Actually I agree with you, and I think the default (without
> specifying the Method) should also produce some sort of message.
>
It's a bug. It should issue a message and return unevaluated (which
is what happened in the development build I checked.)
Brett Champion
Wolfram Research