Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2010

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Kernel crash using Z transform, version 7, windows

  • To: mathgroup at smc.vnet.net
  • Subject: [mg109318] Re: Kernel crash using Z transform, version 7, windows
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Wed, 21 Apr 2010 07:47:42 -0400 (EDT)
  • Reply-to: hanlonr at cox.net

I get the same crash; however, if I both Rationalize AND Simplify (but NOT FullSimplify) first, then

$Version

7.0 for Mac OS X x86 (64-bit) (February 19, 2009)

expr = 0.20056791381984598*I*
    E^((-2.3120000000000003 -
         2.4929211780559766*I)*n) -
   0.20056791381984598*I*
    E^((-2.3120000000000003 +
         2.4929211780559766*I)*n);

expr2 = Rationalize[expr, 0] // Simplify;

ZTransform[expr2, n, z, Method -> "Holonomic"] //
   Simplify // N // Chop

-((0.00019498218407440176*I*
         (123.12233073821176*I*z^2 + 
            19.439038443105282*I*z + 
            1.2082565103472076*I))/
      (z*(0.04455426509374547 + z^2 + 
            0.00009630406771703447/z^2 + 
            0.31576787616922936*z + 
            0.0030987765570423247/z)))


Bob Hanlon

---- "Nasser M. Abbasi" <nma at 12000.org> wrote: 

=============
Warning, do not run this before saving your work:

In[1]:= ClearAll["Global`*"];

expr = 0.20056791381984598*I*E^((-2.3120000000000003 - 
2.4929211780559766*I)*n) -
   0.20056791381984598*I*E^((-2.3120000000000003 + 2.4929211780559766*I)*n);

ZTransform[expr, n, z, Method -> "Holonomic"]

*kernel crash*

But when I do

ZTransform[expr, n, z]

I was getting errors General::lrgexp, but no crash.

The above is an expression generated internally from a program I am working 
on, depending on the input parameters, sometimes I get these errors and 
sometimes I do not, since the expr will be different each time depending on 
the parameters that are entered.

So I was trying to find where the error was coming from. I do not really 
understand why this error message is coming. Must be something internal to 
Ztransform.

I will send a bug report to WRI support also.

--Nasser



--

Bob Hanlon



  • Prev by Date: Re: Using Solve[] - What did I do wrong?
  • Next by Date: Header and Footer Number of Pages
  • Previous by thread: Re: Dynamic evaluation of layered networks
  • Next by thread: Header and Footer Number of Pages