Log2 and beta test failures

[John W. Eaton]

On  5-May-2008, Michael Goffioul wrote:

| I just recompiled development branch of octave (hg source pulled
| a few hours ago) and I notice the following test failures, related
| to log2 and beta:
| 
|   ***** test
|  [f, e] = log2 ([0,-1; 2,-4; Inf,-Inf]);
|  assert (f, [0,-0.5; 0.5,-0.5; Inf,-Inf]);
|  assert (e, [0,1;2,3;0,0])
| !!!!! test failed
| error: assert (f,[0, -0.5; 0.5, -0.5; Inf, -Inf]) expected
|    0.00000  -0.50000
|    0.50000  -0.50000
|        Inf      -Inf
| but got
|    0.00000  -0.50000
|    0.50000  -0.50000
|        NaN       NaN
| NaNs don't match
| 
| 
|   ***** test
|  [f, e] = log2 (complex (zeros (3, 2), [0,-1; 2,-4; Inf,-Inf]));
|  assert (f, complex (zeros (3, 2), [0,-0.5; 0.5,-0.5; Inf,-Inf]));
|  assert (e, [0,1; 2,3; 0,0]);
| !!!!! test failed
| error: assert (f,complex (zeros (3, 2), [0, -0.5; 0.5, -0.5; Inf,
| -Inf])) expected
|    0.00000 + 0.00000i   0.00000 - 0.50000i
|    0.00000 + 0.50000i   0.00000 - 0.50000i
|    0.00000 +     Infi   0.00000 -     Infi
| but got
|    0.00000 + 0.00000i   0.00000 - 0.50000i
|    0.00000 + 0.50000i   0.00000 - 0.50000i
|        NaN -     NaNi       NaN -     NaNi
| NaNs don't match
| 
| 
|   ***** test
|  [v, i] = sort ([NaN, 1i, -1, Inf, 1, 1i]);
|  assert (v, [1, 1i, 1i, -1, Inf, NaN])
|  assert (i, [5, 2, 6, 3, 4, 1])
| !!!!! test failed
| error: assert (i,[5, 2, 6, 3, 4, 1]) expected
|    5   2   6   3   4   1
| but got
|    5   6   2   3   4   1
| values do not match
| shared variables {
|   m2 =
| 
|      1   2
|      3   4
| 
|   flo =  1.0000e-300
|   fhi =  1.0000e+300
| }
| 
|   ***** test
|  a = 0.25 + (0:5) * 0.5;
|  tol = 10 * max (a) * eps;
|  assert (zeros (size (a)), beta (a, -a), tol)
|  assert (zeros (size (a)), beta (-a, a), tol)
| !!!!! test failed
| error: exception encountered in Fortran subroutine dlgams_
| 
| Related to the beta function failure, I observe this, when I run the
| test in octave:
| 
| octave.exe:3>  a = 0.25 + (0:5) * 0.5;
| octave.exe:4>  tol = 10 * max (a) * eps;
| octave.exe:5>  assert (zeros (size (a)), beta (a, -a), tol)
|  ***MESSAGE FROM ROUTINE DGAMMA IN LIBRARY SLATEC.
|  ***FATAL ERROR, PROG ABORTED, TRACEBACK REQUESTED
|  *  X IS 0
|  *  ERROR NUMBER = 4
|  *
|  ***END OF MESSAGE
| 
|  ***JOB ABORT DUE TO FATAL ERROR.
| 0          ERROR MESSAGE SUMMARY
|  LIBRARY    SUBROUTINE MESSAGE START             NERR     LEVEL     COUNT
|  SLATEC     DGAMMA     X IS 0                       4         2         1
| 
| error: exception encountered in Fortran subroutine dlgams_
| error: caught execution error in library function
| error: evaluating binary operator `-' near line 59, column 49
| error: evaluating argument list element number 1
| error: evaluating argument list element number 1
| error: evaluating assignment expression near line 59, column 10
| error: called from `beta' in file
| `D:\Software\VCLibs\local\share\octave\3.0.0+\m\specfun\beta.m'
| 
| Michael.
| 
| error: evaluating argument list element number 2

With GCC 4.2.3 I notice the following failure, but only if I compile
without -O:

     ***** assert(log2(complex(0,Inf)), Inf + log2(i)); 
  !!!!! test failed
  error: assert (log2 (complex (0, Inf)),Inf + log2 (i)) expected
  Inf + 2.266i
  but got
  Inf - NaNi
  NaNs don't match

With the default options (-g -O2) the test succeeds.  I don't have a
solution for this problem, and I can't easily debug the problem with
the Windows build.

jwe