Fortran Wiki
system_clock (Rev #3, changes)

Showing changes from revision #2 to #3: (追記) Added (追記ここまで) | ~~(削除) Removed (削除ここまで)~~ | ~~(削除) Chan (削除ここまで)~~(追記) ged (追記ここまで)

Description

~~(削除) Determines the (削除ここまで)~~(追記) SYSTEM_CLOCK(f95) (追記ここまで)~~(削除) count (削除ここまで)~~(追記) lets you measure durations of time with the precision of the smallest time increment generally available on a system by returning processor-dependent values based on the current value of the processor clock. The (追記ここまで)~~(削除) of milliseconds of wall clock time since the Epoch (00:00:00 UTC, January 1, 1970) modulo (削除ここまで)~~(追記) clock (追記ここまで)(追記) value is incremented by one for each clock count until the value (追記ここまで)count_max~~(削除) , (削除ここまで)~~(追記) (追記ここまで)(追記) is (追記ここまで)(追記) reached (追記ここまで)(追記) and (追記ここまで)(追記) is (追記ここまで)(追記) then (追記ここまで)(追記) reset (追記ここまで)(追記) to (追記ここまで)(追記) zero (追記ここまで)(追記) at (追記ここまで)(追記) the (追記ここまで)(追記) next (追記ここまで)(追記) count. (追記ここまで)(追記) clock (追記ここまで)(追記) therefore is a modulo value that lies in the range 0 to (追記ここまで)(追記) count_max (追記ここまで)(追記) . (追記ここまで)count_rate ~~(削除) determines (削除ここまで)~~(追記) and (追記ここまで)~~(削除) the (削除ここまで)(削除) number (削除ここまで)(削除) of (削除ここまで)(削除) clock (削除ここまで)(削除) ticks (削除ここまで)(削除) per (削除ここまで)(削除) second. (削除ここまで)(削除) count_rate (削除ここまで)(削除) and (削除ここまで)~~count_max are(追記) assumed (追記ここまで) constant~~(削除) and (削除ここまで)~~(追記) (even (追記ここまで)~~(削除) specific (削除ここまで)~~(追記) though (追記ここまで)~~(削除) to (削除ここまで)~~(追記) CPU (追記ここまで)(追記) rates (追記ここまで)(追記) can (追記ここまで)(追記) vary (追記ここまで)(追記) on (追記ここまで)(追記) a (追記ここまで)(追記) single (追記ここまで)(追記) platform). (追記ここまで)(削除) gfortran (削除ここまで)(追記) count_rate (追記ここまで)~~(削除) . (削除ここまで)~~(追記) (追記ここまで)(追記) reports (追記ここまで)(追記) the (追記ここまで)(追記) number (追記ここまで)(追記) of (追記ここまで)(追記) clock (追記ここまで)(追記) ticks (追記ここまで)(追記) per (追記ここまで)(追記) second, (追記ここまで)(追記) allowing (追記ここまで)(追記) clock (追記ここまで)(追記) values to be translated from clock clicks to seconds. (追記ここまで)

If there is no clock, count is set to -huge(count), and count_rate and count_max are set to~~(削除) zero (削除ここまで)~~(追記) zero. (追記ここまで)

(追記)

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.

(追記ここまで)(追記) (追記ここまで)

Standard

Fortran 95 and later

Class

Subroutine

Syntax

call system_clock([count, count_rate, count_max])

Arguments

count - (Optional) shall be a scalar of type~~(削除) default (削除ここまで)~~integer with intent(out).
count_rate - (Optional) shall be a scalar of type~~(削除) default (削除ここまで)~~integer(追記) or (追記ここまで)(追記) real (追記ここまで) with intent(out).
count_max - (Optional) shall be a scalar of type~~(削除) default (削除ここまで)~~integer with intent(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

Fortran Wiki system_clock (Rev #3, changes)