Fortran: Difference between revisions
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== Timing == | == Timing == | ||
system_clock tells the elapsed wall time between two successive calls. | system_clock tells the elapsed wall time between two successive calls. | ||
< | <syntaxhighlight lang='fortran'> | ||
integer(kind=8):: tclock1, tclock2, clock_rate | integer(kind=8):: tclock1, tclock2, clock_rate | ||
real(kind=8):: elapse_time | real(kind=8):: elapse_time | ||
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call system_clock(tclock2, clock_rate) | call system_clock(tclock2, clock_rate) | ||
elapse_time = float(tclock2 - tclock1) / float(clock_rate) | elapse_time = float(tclock2 - tclock1) / float(clock_rate) | ||
</ | </syntaxhighlight> | ||
cpu_time tells the CPU time used between two successive calls | cpu_time tells the CPU time used between two successive calls | ||
< | <syntaxhighlight lang='fortran'> | ||
real(kind=8):: t1, t2, elapsed_cpu_time | real(kind=8):: t1, t2, elapsed_cpu_time | ||
call cpu_time(t1) | call cpu_time(t1) | ||
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call cpu_time(t2) | call cpu_time(t2) | ||
elapsed_cpu_time = t2 - t1 | elapsed_cpu_time = t2 - t1 | ||
</ | </syntaxhighlight> | ||
Since Unix provides a timing command called '''time''', we can compare the system time and cpu time reported by Fortran's functions and Unix's time command; e.g. '''time ./a.out''' where a.out is the executable file written by a Fortran code. See an example from '''the High Performance Scientific Computing''' (University of Washington); the [http://faculty.washington.edu/rjl/uwhpsc-coursera/index.html web lecture] and the [https://class.coursera.org/scicomp-003/lecture/197 video lecture]. | Since Unix provides a timing command called '''time''', we can compare the system time and cpu time reported by Fortran's functions and Unix's time command; e.g. '''time ./a.out''' where a.out is the executable file written by a Fortran code. See an example from '''the High Performance Scientific Computing''' (University of Washington); the [http://faculty.washington.edu/rjl/uwhpsc-coursera/index.html web lecture] and the [https://class.coursera.org/scicomp-003/lecture/197 video lecture]. | ||
Revision as of 12:46, 16 November 2015
Misc
Change stack size
In Compaq Visual Fortran, go to Project Settings -> Win32 Release -> Link. In the Project Options text box, add something like /stack:0x989680 (the decimal value is 10000000 or 10MB).
Timing
system_clock tells the elapsed wall time between two successive calls.
integer(kind=8):: tclock1, tclock2, clock_rate real(kind=8):: elapse_time call system_clock(tclock1) <code to be timed> call system_clock(tclock2, clock_rate) elapse_time = float(tclock2 - tclock1) / float(clock_rate)
cpu_time tells the CPU time used between two successive calls
real(kind=8):: t1, t2, elapsed_cpu_time call cpu_time(t1) <code to be timed> call cpu_time(t2) elapsed_cpu_time = t2 - t1
Since Unix provides a timing command called time, we can compare the system time and cpu time reported by Fortran's functions and Unix's time command; e.g. time ./a.out where a.out is the executable file written by a Fortran code. See an example from the High Performance Scientific Computing (University of Washington); the web lecture and the video lecture.