# 0.65/AIX

**Peter Dalgaard BSA
**
p.dalgaard@biostat.ku.dk

*14 Jul 1999 00:12:48 +0200*

Kurt Hornik <Kurt.Hornik@ci.tuwien.ac.at> writes:
>* On the system I have access to, I can compile only with
*>*
*>* -D_XOPEN_SOURCE_EXTENDED=2 (VERY noisy)
*>* or
*>* -D_ALL_SOURCE
*>*
*>* In either case, we get the above.
*>*
*>* I will hence use ALL_SOURCE for the time being.
*>*
*>* Note that
*>*
*>* > 1/0 - 1/0# NaN
*>* [1]NaNQ
*>* > is.nan(1/0 - 1/0)
*>* [1] TRUE
*>*
*>* so what is really going on here???
*
Double "hmmmm"....
Can you run this under gdb? If so, could you set a breakpoint in
EncodeReal and step through it?
That'll be (roughly)
R -d gdb
(gdb) run
^C
(gdb) break EncodeReal
(gdb) continue
>* 1/0
*(gdb) next
<etc.>
I bet it never enters the "if (!R_FINITE(x))" branch as it should.
This could happen if HAVE_FINITE and IEEE_754 are both undefined in
Arith.h, or if finite(x) doesn't work in the IEEE way.
>*From what Martin has been telling us, AIX is using IEEE format numbers
*and arithmetic anyhow, so it should be fairly easy to fudge a better
R_FINITE (and ISNAN too). I think we went through some of that last
time we had R_FINITE/ISNAN and friends on the board, didn't we?
Something pretty close to the following should work:
#define R_FINITE(x) ({double y = x; \
*((int *) &y) & 0x7ff00000 != 0x7ff00000})
#define ISNAN(x) ({double y = x; \
*((int *) &y) & 0x7ff00000 == 0x7ff00000 && \
(*((int *) &y) & 0x7fffffff != 0x7ff00000 || *((int *) &y + 1) != 0)}
Of course, that kind of code is pretty architecture dependent, etc...
Perhaps one should first check what the status of IEEE macros in AIX
really is.
--
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk) FAX: (+45) 35327907
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