IEEE_754 logic

[Thomas Hoffmann]

Can anybody of the architects of R enlighten me about the reasoning behind the selection of the IEEE 754 
mode for the building of R, please?

Special points of interest are:

1. The selection seems to be based on the availability of isnan() and finite(). Is this a common way 
to test for IEEE 754?

2. The C9x draft introduces isfinite() instead of finite() (and as I see, some systems, e.g. the 
macintosh, use this naming already). This is a deviation from the old ieee754 C mapping. I do not 
know, where we are in this transformation process now (most compilers seem to use finite(), still).

3. The C9x draft introduces the is*() functionality under the name of "classification MACROS". If an 
implementation implements this standard, autoconf misses isnan() and isfinite().

=============================================================================
Thomas Hoffmann, Institut fuer Halbleiter- und Mikrosystemtechnik, TU Dresden 
E-mail: hoffmann@ehmgs2.et.tu-dresden.de

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