首页 > IT职业 > IT生活 > ZT - 怎样提高调用数学函数的程序的性能(6)
下面是一个用于计时 DFT 代码的 Fortran 驱动器程序。
program main
interface
subroutine dft(x,a,phi,n)
real*8 x(n),a(n),phi(n)
integer n
end subroutine
subroutine init(a,n)
real*8 a(n)
integer n
end subroutine
subroutine consume(a,b,c)
real*8 a(*),b(*),c(*)
end subroutine
end interface
! Parameters:
! nmax is the problem size.
! nrep is the number of repetitions of the
! problem. This should be chosen so that
! the elapsed time is long enough to give
! sufficient timing resolution.
! cyc is the clock frequency in Hz for the
! processor that the program is to be run on.
! (Can be found from AIX command pmcycles.)
integer, parameter :: nmax=1000
integer, parameter :: nrep=100
real*8, parameter :: cyc=4704000000.d0
real*8 x(nmax), a(nmax), phi(nmax)
real*8 tx, ty, accum, del(4)
intrinsic sin, sqrt
real*8 rtc
del(4)=0.d0
acc = 0.d0
do k=1,nrep
tx=rtc()
call init(x,nmax)
call dft(x,a,phi,nmax)
ty=rtc()
call consume(x,a,phi)
do j=1,nmax
acc = acc + a(j) + phi(j)
end do
del(4) = del(4) + (ty-tx)
end do
del(1) = del(4)/real(nmax,8)
del(2) = del(1)/real(nrep,8)
del(3) = cyc*del(2)
print *,'acc=',acc/real(nrep,8),' n=',nmax,
& ' r=',nrep, ' a=',del(1),' b=',del(2),
& ' c=',del(3),' w=',del(4)
end program
|
来自 “ ITPUB博客 ” ,链接:https://blog.itpub.net/16896827/viewspace-1036479/ ,如需转载,请注明出处,否则将追究法律责任。