problem with the exponential function on the NeXT
- To: mathgroup at yoda.physics.unc.edu
- Subject: problem with the exponential function on the NeXT
- From: herrmann at siam.math.tamu.edu (joe herrmann)
- Date: Sat, 26 Dec 1992 16:54:36 -0600
Dear math group,
I found this working on my research about the energy input to cracks in
inhomogeneous materials. I was using Airy functions and got a strange value at one point.
After checking Abramowitz and Stegun (p148) (10.4.59) I tried their asymptotic formula for
the Airy function and found what was happening was a problem with the exponential
function.
Mathematica 2.0 for NeXT
Copyright 1988-91 Wolfram Research, Inc.
In[8]
Table[N[E^x],{x,-700000,-600000,5000}]
Out[8]
-304007 -301835
{7.288996199 10 , 2.163103201 10 ,
-299664 -297492
6.419286457 10 , 1.905005669 10 ,
-295321 -293149
5.653348896 10 , 1.677703865 10 ,
56 -288806
2.51105 10 , 1.4775232975 10 ,
-286635 -284463
4.384740076 10 , 1.3012279106 10 ,
-282292 -280120
3.861560881 10 , 1.1459677678 10 ,
-277949 -275777
3.400806475 10 , 1.0092329824 10 ,
-273606 22
2.995028445 10 , 1.40101 10 ,
-269263 -267092
2.637667109 10 , 7.827615781 10 ,
-264920 -262749
2.322945477 10 , 6.893638932 10 ,
-260577
2.045775856 10 }
Note the incorrect results at -670,000 and -625,000. I had a friend check this on his Sun
and mathematica gave no incorrect answers in his test so it may only be a problem on the
NeXT.
Can you tell me what is happening? Is there a fix?
Thank you.
Sincerely,
Joe Herrmann
Texas A&M Math Dept
herrmann at siam.tamu.edu