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- From: aicklen@utdallas.edu (Greg Aicklen)
- Newsgroups: sci.math.symbolic
- Subject: Inconsistent Mma results across platforms?
- Message-ID: <1992Nov6.154109.6056@utdallas.edu>
- Date: 6 Nov 92 15:41:09 GMT
- Article-I.D.: utdallas.1992Nov6.154109.6056
- Sender: aicklen@utdallas.edu (Gregory H. Aicklen)
- Organization: Univ. of Texas at Dallas
- Lines: 110
- Nntp-Posting-Host: drips.utdallas.edu
-
- I am running the same version of Mma (2.1) on two different platforms and I
- get different results in a symbolic operation. Note that I am running the
- Windows version of Mma 2.1, Student Edition on a 386SX with 10MB of RAM.
-
- I seem to get different answers from ComplexExpand[] between the SPARC and
- PC (windows) implementations of Mma 2.1. Here is an example:
-
- Mathematica 2.1 for SPARC
- Copyright 1988-92 Wolfram Research, Inc.
- -- X11 windows graphics initialized --
-
- In[1]:= eta = .
-
- In[2]:= xbar = .
-
- In[3]:= q[x_,t_] := 2 eta Sech[2 eta (x -xbar)] E^(4 I eta^2 t)
-
- In[4]:= eta = 1;
-
- In[5]:= xbar = 0;
-
- In[6]:= qt[x_,t_] = D[q[x,t], t]
-
- 4 I t
- Out[6]= 8 I E Sech[2 x]
-
- In[7]:= qxx[x_,t_] = D[q[x,t], {x,2}]
-
- 4 I t 3 4 I t 2
- Out[7]= -8 E Sech[2 x] + 8 E Sech[2 x] Tanh[2 x]
-
- In[8]:= fnls[x_,t_] = qt[x,t] - I qxx[x,t] - 2 I q[x,t]^2 Conjugate[q[x,t]]
-
- 4 I t 8 I t 4 I t
- Out[8]= 8 I E Sech[2 x] - 8 I E Conjugate[2 E Sech[2 x]]
-
- 2 4 I t 3 4 I t 2
- > Sech[2 x] - I (-8 E Sech[2 x] + 8 E Sech[2 x] Tanh[2 x] )
-
- In[9]:= nls = fnls[x,t]
-
- 4 I t 8 I t 4 I t
- Out[9]= 8 I E Sech[2 x] - 8 I E Conjugate[2 E Sech[2 x]]
-
- 2 4 I t 3 4 I t 2
- > Sech[2 x] - I (-8 E Sech[2 x] + 8 E Sech[2 x] Tanh[2 x] )
-
- In[10]:= nls = ComplexExpand[nls, TargetFunctions->{Re, Im}]
-
- 3
- -64 Cosh[2 x] Sin[4 t] 16 Cosh[2 x] Sin[4 t]
- Out[10]= ----------------------- - --------------------- +
- 3 1 + Cosh[4 x]
- (1 + Cosh[4 x])
-
- 2 -32 Cos[8 t] Cosh[2 x] Sin[4 t]
- > (4 Cosh[2 x] (------------------------------- +
- 1 + Cosh[4 x]
-
- 32 Cos[4 t] Cosh[2 x] Sin[8 t] 2
- > ------------------------------)) / (1 + Cosh[4 x]) +
- 1 + Cosh[4 x]
-
- 2
- 16 Cosh[2 x] Sin[4 t] Sinh[4 x]
- > -------------------------------- +
- 3
- (1 + Cosh[4 x])
-
- 3
- 64 Cos[4 t] Cosh[2 x] 16 Cos[4 t] Cosh[2 x]
- > I (---------------------- + --------------------- +
- 3 1 + Cosh[4 x]
- (1 + Cosh[4 x])
-
- 2 -32 Cos[4 t] Cos[8 t] Cosh[2 x]
- > (4 Cosh[2 x] (------------------------------- -
- 1 + Cosh[4 x]
-
- 32 Cosh[2 x] Sin[4 t] Sin[8 t] 2
- > ------------------------------)) / (1 + Cosh[4 x]) -
- 1 + Cosh[4 x]
-
- 2
- 16 Cos[4 t] Cosh[2 x] Sinh[4 x]
- > --------------------------------)
- 3
- (1 + Cosh[4 x])
-
- In[11]:= Simplify[nls]
-
- Out[11]= 0
-
- In[12]:=Quit
-
- For the Windows version 2.1 (Student Version), the result of the ComplexExpand[] is
-
- 3
- Sech[2 x] (8 (-2 + 2 Cos[8 t]) Sin[4 t] + 16 Cos[4 t] Sin[8 t]) +
-
- 3
- I Sech[2 x] (-8 Cos[4 t] (-2 + 2 Cos[8 t]) + 16 Sin[4 t] Sin[8 t])
-
- and I (obviously) can't reduce this to zero.
-
-
- Any ideas? Anybody else able to duplicate this or seen something similar?
-
- Greg Aicklen
- aicklen@utdallas.edu
-