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