something (not) funny!
- To: mathgroup at smc.vnet.net
- Subject: [mg79978] something (not) funny!
- From: dimitris <dimmechan at yahoo.com>
- Date: Fri, 10 Aug 2007 01:42:23 -0400 (EDT)
CAS (Mathematica 5.2 in particular) can be funny sometimes!
[Seriously now, I understand the difficulties and the problems
that appeared possibly in the following examples and more or less
I can figure what goes wrong.
Note that one of this examples appeared in a recent post
of someone leading him to wonder about the reliability of Mathematica.
That's why we should trust but verify results from CASs...
Anyway, since for someone-not me!- it is vacation period
it is needed some fun!]
Version->5.2
Example 1
In[1]:=
Timing[FourierTransform[Sech[x*a], x, s]]
Out[1]=
{58.359*Second, (Sqrt[Pi/2]*Sech[(Pi*s)/(2*a)])/a}
However,
In[2]:=
TimeConstrained[FourierTransform[Sech[x*Log[2]], x, s], 300]
Out[2]=
$Aborted
Example 2
In[4]:=
TrigToExp[Sech[x*a]]
FourierTransform[%, x, s]
Out[4]=
2/(E^((-a)*x) + E^(a*x))
Out[4]=
(Sqrt[Pi/2]*Sech[(Pi*s)/(2*a)])/a
In[5]:=
TrigToExp[Sech[x*Log[2]]]
FourierTransform[%, x, s]
Out[5]=
2/(2^(-x) + 2^x)
Out[5]=
FourierTransform[2/(2^(-x) + 2^x), x, s]
Dimitris