Re: NMinimize Bug in Mathematica 7.0?
- To: mathgroup at smc.vnet.net
- Subject: [mg96243] Re: NMinimize Bug in Mathematica 7.0?
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Tue, 10 Feb 2009 05:49:58 -0500 (EST)
- Organization: The Open University, Milton Keynes, UK
- References: <gmp0pi$c02$1@smc.vnet.net>
In article <gmp0pi$c02$1 at smc.vnet.net>, appris at att.net wrote:
> Here is an example from Mathematica's user's guide:
>
> In[8]:= NMinimize[x^4 - 3 x^2 + x, x]
>
> Out[8]= {-3.513905039, {x -> -1.300839566}}
>
> however, trying to replicate it, I get the following:
>
> In[2]:= NMinimize[x^4 - 3 x^2 + x, x]
>
> Out[2]= {-1.070230182, {x -> 1.130901122}}
>
> One way to find the global min, I had to use a constraint such as x<0.
>
> Has anyone come across such a problem?
>
> In[3]:= $Version
>
> Out[3]= "7.0 for Microsoft Windows (32-bit) (November 10, 2008)"
I bet that the example you posted (In[8]/Ou[8]) ran on Mathematica 5.x
because the function NMinimize[] was introduced in Mathematica 5.0 and
updated/modified/fixed(broken? :-) in version 6.0 (according to the
online documentation). I get the same result as yours in Mathematica
6.0.3 for Mac OS X and 7.0 for Windows XP.
In[4]:= $Version
Out[4]= "6.0 for Mac OS X x86 (64-bit) (May 21, 2008)"
In[5]:= NMinimize[x^4 - 3 x^2 + x, x]
Out[5]= {-1.07023, {x -> 1.1309}}
In[7]:= NMinimize[{x^4 - 3 x^2 + x, x < 0}, x]
Out[7]= {-3.51391, {x -> -1.30084}}
In[17]:= $Version
Out[17]= "7.0 for Microsoft Windows (32-bit) (November 10, 2008)"
In[18]:= NMinimize[x^4 - 3 x^2 + x, x]
Out[18]= {-1.07023, {x -> 1.1309}}
In[19]:= NMinimize[{x^4 - 3 x^2 + x, x < 0}, x]
Out[19]= {-3.51391, {x -> -1.30084}}
Regards,
--Jean-Marc