Mathematica 9 is now available
Student Support Forum
-----
Student Support Forum: 'NMaximize with constraints' topicStudent Support Forum > General > Archives > "NMaximize with constraints"

< Previous Comment | Next Comment >Help | Reply To Comment | Reply To Topic
Author Comment/Response
Bill Simpson
07/04/12 4:08pm

In Response To 'Re: Re: Re: Re: NMaximize with constraints'
---------
Please excuse my mangling this into ascii text. See if you can reproduce what I see.

Working strictly with only your first cell,
Temporarily modify your LambdaIP definition to be

LambdaIP:=Piecewise[
{{Print[{"LIP 0 ", t Alpha MuIP MuT}];1,t Alpha MuIP MuT==0}},
<<youroriginalLambdaIPdefinition>>];

Temporarily modify your LambdaT definition to be

LambdaT:=Piecewise[
{{Print[{"LT 0 ", 2t^2(-1+Alpha)Alpha^2 MuIP^3 MuT}];1, 2t^2 (-1+Alpha)Alpha^2 MuIP^3 MuT==0}},
<<your originalLambdaTdefinition>>];

What that is trying to do is "guard" your two denominators. It tests each denominator to see if they are zero and if so prints a warning 0 and substitutes a meaningless 1 instead of your original expression, otherwise it just uses your original expression.

All that should do is just use up cycles if neither denominator were ever zero.

But what I am seeing in

From In[14]:= {LIP 0, 600. MuIP MuT}
From In[14]:= {LT 0, -288000. MuIP^3 MuT}
From In[14]:= {LT 0, -288000. MuIP^3 MuT}
From In[14]:= {LIP 0, 600. MuIP MuT}
From In[14]:= {LT 0, -288000. MuIP^3 MuT}

So it looks like your denominators equal zero and are not numeric values all at the same time.

The reason I did all this was because I was seeing the warning messages about values not being Real in NMinimize. I suspected this was because of a negative value inside your Sqrt and wanted to verify this with a Piecewise guard.

If you very carefully construct a similar Piecewise guard around your Sqrt argument you may see similar warnings that the argument appears to be both less than zero and not numeric all at the same time.

Note: substituting those senseless 1's for the original senseless values does generate a few spurious warnings that need to be ignored.

If there are no mistakes in this then this may provide some clues to track down the source of your concerns that your constraints are not being respected.

Perhaps this is just one more pitfall of the widespread overwhelming compulsion to use subscripts. Perhaps not.

URL: ,

Subject (listing for 'NMaximize with constraints')
Author Date Posted
NMaximize with constraints alab 06/28/12 00:22am
Re: NMaximize with constraints Michael 06/30/12 7:28pm
Re: Re: NMaximize with constraints alab 06/30/12 10:11pm
Re: Re: Re: NMaximize with constraints Michael 07/01/12 11:14pm
Re: Re: Re: Re: NMaximize with constraints ala 07/02/12 11:54am
Re: Re: Re: Re: Re: NMaximize with constraints Bill Simpson 07/04/12 4:08pm
Re: Re: Re: Re: Re: Re: NMaximize with constrai... alab 07/04/12 9:41pm
< Previous Comment | Next Comment >Help | Reply To Comment | Reply To Topic