Re: Problem with parametric minimization
- To: mathgroup at smc.vnet.net
- Subject: [mg90254] Re: Problem with parametric minimization
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Thu, 3 Jul 2008 06:13:32 -0400 (EDT)
- Organization: The Open University, Milton Keynes, UK
- References: <g4fhkl$9gs$1@smc.vnet.net>
Stephan Heckmueller wrote:
> I have a problem with with the examples for using the
> Minimize function given in the documentation on wolfram.com:
>
> When trying:
>
> Minimize[ax^2+bx+c,x]
>
> I receive the following error:
>
> Minimize::objv:
> The objective function c+bx+ax^2 contains a nonconstant
> expression c independent of variables (x).
>
> Is there something wrong with the command or the
> documentation?
Starting from a fresh kernel, I do not get any error message when
evaluating the expression you posted:
In[1]:= Minimize[ax^2 + bx + c, x]
Out[1]= {ax^2 + bx + c, {x -> 0}}
Though I strongly suspect that what you intended was the following (note
that you must either put a space between coefficients and variables --
implicit multiplication -- or add a star between them, otherwise you
just declare some variables called 'ax' and 'bx'):
In[2]:= Minimize[a*x^2 + b*x + c, x]
Out[2]= {Piecewise[{{c, (b == 0 && a == 0) || (b == 0 && a > 0)},
2
-b + 4 a c
{-----------, (b > 0 && a > 0) || (b < 0 && a > 0)}}, -Infinity],
4 a
{x -> Piecewise[{{0, (b == 0 && a == 0) || (b == 0 && a > 0)},
b
{-(---), (b > 0 && a > 0) || (b < 0 && a > 0)}}, Indeterminate]}}
2 a
Regards,
-- Jean-Marc