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system_clock (Rev #3, changes)
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Description
Determines the SYSTEM_CLOCK(f95)count of milliseconds of wall clock time since the Epoch (00:00:00 UTC, January 1, 1970) modulo clock value is incremented by one for each clock count until the value count_max , is reached and is then reset to zero at the next count.clock therefore is a modulo value that lies in the range 0 to count_max. count_rate determines and the number of clock ticks per second.count_rate and count_max are assumed constant and (even specific though to CPU rates can vary on a single platform). gfortran count_rate . reports the number of clock ticks per second, allowingclock values to be translated from clock clicks to seconds.
If there is no clock, count is set to -huge(count), and count_rate and count_max are set to zero zero.
SYSTEM_CLOCK(f95) is typically used to measure short time intervals (system clocks may be 24-hour clocks or measure processor clock ticks since boot, for example). It is most often used for measuring or tracking the time spent in code blocks in lieu of using profiling tools.
Standard
Fortran 95 and later
Class
Subroutine
Syntax
call system_clock([count, count_rate, count_max])
Arguments
count- (Optional) shall be a scalar of typedefaultintegerwithintent(out).count_rate- (Optional) shall be a scalar of typedefaultintegerorrealwithintent(out).count_max- (Optional) shall be a scalar of typedefaultintegerwithintent(out).
Example
program test_system_clock integer :: count, count_rate, count_max call system_clock(count, count_rate, count_max) write(*,*) count, count_rate, count_max end program