The IEEE standard for binary floating point arithmetic ([&make_named_href('',
"node12.html#IEEE:BFPA","[13]")])
specifies how machines conforming to the standard should represent floating
point values. We refer to machines conforming to this standard as IEEE
machines
. Thus, when we communicate floating point numbers
between IEEE machines we might hope that each processor has the same value. This
is a reasonable hope and will often be realized.
For example, XDR (External Data Representation, [&make_named_href('',
"node12.html#SunSoft:XDR","[19]")]) uses
the IEEE representation for floating point numbers and so a message passing
system that uses XDR will communicate floating point numbers without
change. PVM is an example of a system that uses XDR. MPI
suggests the use of XDR, but does not mandate its use ([&make_named_href('',
"node12.html#SOHWD:96","[18]"), Section
2.3.3,]). Unless we have additional information about the
implementation we cannot assume that floating point numbers will be communicated
without change on IEEE machines when using MPI.
Note that there is also an IEEE standard concerned with standardizing data formats to aid data conversion between processors ([&make_named_href('', "node12.html#IEEE:SDFOfSCIP","[15]")]).