(j3.2006) (SC22WG5.4099) [ukfortran] Standard intrinsics and coarrays
Wed Oct 21 12:19:47 EDT 2009
N.M. Maclaren wrote:
> This is a redraft, hopefully fixing all of the mistakes and ambiguities
> pointed out by Bill.
> We seem to have forgotten to specify how the intrinsic procedures may
> be used as far as their use in unordered images is concerned - or, at
> least, I can't find anything. However, I don't think that there is much
> of a problem. 13.5 paragraph 2 and Table 13.1 is the starting point,
> and a lot of my proposal is already implied for those of classes E, ES
> and PS by other wording. Those of class A are already covered.
> I have drafted the hard line on random numbers; it would be possible to
> make the 'shall be' conditional on the processor dependence, but that is
Taking into account recent messages, here are some suggested changes:
> In 13.5, Standard generic intrinsic procedures, after Table 13.1, add
> the new paragraphs:
I believe that this first paragraph should also include comments on
GET_ENVIRONMENT_VARIABLE, GET_COMMAND, GET_COMMAND_ARGUMENT, and
COMMAND_ARGUMENT_COUNT. All of these routines involve communication with
the user's shell.
Calling any of these from image 1 should produce the expected result,
and that the effects on images other than 1 are processor dependent.
> It is processor dependent whether EXECUTE_COMMAND_LINE may be called
> on any image other than image 1.
We need to be careful that calling RANDOM_SEED and RANDOM_NUMBER within
the same segment is still allowed (i.e. when A and B are the same.) The
random number generator is an intrinsic library routine that happens to
have internal state, so is a unique case and deserves its own paragraph.
> If RANDOM_SEED is called in a segment A, and either RANDOM_SEED or
> RANDOM_NUMBER is called in segment B, then segments A and B shall be
> ordered. It is processor dependent whether all images use a common
> generator or whether each image uses a separate one.
I would pare this down to CPU_TIME, DATE_AND_TIME, and SYSTEM_CLOCK.
They are closely related and involve direct interaction with the OS or
> It is processor dependent whether the results returned from CPU_TIME,
> DATE_AND_TIME, GET_COMMAND, GET_COMMAND_ARGUMENT,
> GET_ENVIRONMENT_VARIABLE and SYSTEM_CLOCK are dependent on which
> image calls them.
> NOTE 13.x
> It is unspecified whether images use synchronized clocks, whether
> CPU_TIME returns a per-image or per-program value, whether all
> images run in the same time zone, whether the count rate and
> maximum in SYSTEM_CLOCK are the same for all images
I would then end the NOTE at this point.
, and whether all
> images run in the same command environment. It is likely that they
> will behave differently on shared memory systems and some
> distributed memory ones.
> The use of all other standard intrinsic procedures in unordered
> segments is subject only to their argument use following the rules
> in 8.5.2.
> Nick Maclaren.
> J3 mailing list
> J3 at j3-fortran.org
Bill Long longb at cray.com
Fortran Technical Support & voice: 651-605-9024
Bioinformatics Software Development fax: 651-605-9142
Cray Inc., 1340 Mendota Heights Rd., Mendota Heights, MN, 55120
More information about the J3