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