From octave-maintainers-request at bevo dot che dot wisc dot edu  Mon May 10 12:43:04 1999
Subject: bug in expm
From: "Ross A. Lippert" <ripper at cs dot sandia dot gov>
To: octave-maintainers at bevo dot che dot wisc dot edu
Date: Mon, 10 May 1999 11:42:31 -0600


Below is a really strange error in expm.  I am using octave-2.1.14
on solaris 2.6.


-r


octave:126> yp
yp =

 Columns 1 through 3:

  -4.72e-16 - 7.58e-17i  -8.71e-01 - 2.38e-16i  -5.12e-01 - 8.31e-16i
   2.54e-16 - 4.03e-17i  -3.86e-16 + 3.62e-16i  -1.70e+00 + 1.09e-16i
  -7.21e-18 + 3.35e-18i  -6.97e-17 - 2.49e-17i   4.78e-16 - 1.83e-16i
  -1.36e-31 - 1.85e-32i   2.42e-17 - 1.12e-17i  -2.55e-16 + 2.32e-16i

 Column 4:

   1.50e+00 - 3.97e-16i
   1.38e+00 - 4.57e-16i
  -2.60e-01 + 3.72e-16i
   4.44e-17 - 1.03e-16i

octave:127> expm(yp)
ans = [](0x0)
octave:128> format hex
octave:129> yp
yp =

 Columns 1 and 2:

  bcc10001ac1c251c  bc95dae77a2df5e0i  bfebdc8140000000 
bcb12f69c2a5a200i
  3cb2569249b88fe0  bc873b79c3717e54i  bcbbcb24f5517664 
3cba0fccee5b3e64i
  bc609fd99ffffd00  3c4eded4bd7c1040i  bc9414f755116ee8 
bc7cbd46cc9f7a38i
  b986000000000000  b958000000000000i  3c7bdc81400003f0 
bc69de4b411bf000i

 Columns 3 and 4:

  bfe0664cd05b4fce  bccdefb419800000i  3ff7f757d4e39194 
bcbc9b6000000000i
  bffb2e2e5fffffff  3c9f50272a12f000i  3ff60a476020674b 
bcc07a09f7580000i
  3cc1360af7324175  bcaa516fe711e9d0i  bfd09fd9a0000007 
3cbac57c21c0b400i
  bcb25fd08cea77fa  3cb0b7d9835c9342i  3c8992d544106450 
bc9dc193f84a64e0i