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Re: Probably memory problem

  • To: mathgroup at
  • Subject: [mg88075] Re: Probably memory problem
  • From: Szabolcs Horvát <szhorvat at>
  • Date: Wed, 23 Apr 2008 06:05:10 -0400 (EDT)
  • Organization: University of Bergen
  • References: <fumr02$sef$>

Alejandra Lozada wrote:
> Dear MathGroup,
> _____________________________________
> Question:
> Do anyone knows if using the palletes (Alebraic Manipulation,
> BasicMathInput,
> BasicTypesetting) in Mathematica 6 needs more stack memory that writing
> algebra in full form?
> ______________________________________
> Problem:
> I am interested in check an equality:
> Side 1= Side 2 of the form:
> 24*n*y*y=-4*b+2*v*z-v*v/k*e^z
> With y,b,v,z,k,n variables which all but n
> are veeeeeery long expressions of the form:
> y:=
> b:=
> etc...
> and to make them look shorter I defined other
> expressions, so that y, b, v, etc, need
> other expressions to be complete.
> I know that the equality is analitically true, but
> I get using TrueQ(side 1, side2), PossibleZeroQ,
> that the equality is False.

First, you have to use correct syntax:

Equality is ==, not =
Did you mean E^z when where you've written e^z?
Functions are written with square brackets, TrueQ[expr], not TrueQ(expr)

TrueQ is a structural (not Mathematica operation).  It will only return 
True is the input is explicitly True.

Use Simplify/FullSimplify with appropriate assumptions to check whether 
the equality is true.

> __________________________________________
> Options:
> So, I think that the problem could be in:
> - Lack of memory, because Mathematica stops evaluating
> the notebook after the 16th definition,

What do you mean when you say that Mathematica stops evaluating the 
notebook?  This is very vague.  Do you get an error message?  Does the 
kernel quit?

> although I asked Mathematica about the memory used:
> MemoryInUse= 6,314,760 bites just before it stopped
> evaluating the notebook but I think Mathematica=B4s limit
> is about 19,654,528 bites.
> -Maybe I do not have enough computer memory, but
> I have 1GBite of RAM=1,073,741,824 bites.
> -Maybe I did not write well the definitions.
> ___________________________________________
> Any comments or suggestions will be very appreciated, :)
> thank you very much in advance,
> Alejandra Lozada

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