MPI梯形积分法（Fortran）
MPI 梯形积分法（Fortran）
使⽤MPI分布式接⼝，Fortran语⾔实现，梯形积分法实现计算函数积分，下⾯的代码中⽰例函数是 y=x^2，可以在 f(x)中修改成其他函数。
做梦梦见掉牙齿是什么意思program main
u mpi
implicit none
! MPI 相关变量
integer :: rank, size, ierr, stat(MPI_STATUS_SIZE), i
强干弱枝! 运算相关变量
real :: a, b, h, local_a, local_b, local_n, local_total, total
integer :: n
! 计算运算时间相关变量
real(8) :: start_time, finish_time
real :: local_elapd, elapd
! 函数声明
real, external :: trap
! 初始化
call MPI_INIT(ierr)
call MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr)
call MPI_COMM_SIZE(MPI_COMM_WORLD, size, ierr)
! 获取输⼊房地产信贷
call get_input(rank, size, stat, ierr, a, b, n)
取信于民!
同步各进程，各进程开始计时
call MPI_BARRIER(MPI_COMM_WORLD, ierr)
start_time = MPI_WTIME()
! 各进程计算
h = (b - a) / n
local_n = n / size
local_a = a + rank*local_n*h
local_b = local_a + local_n*h
local_total = trap(local_a, local_b, local_n, h)
! 求和并发送到0号进程
call MPI_REDUCE(local_total, total, 1, MPI_REAL, MPI_SUM, 0, MPI_COMM_WORLD, ierr)
!
计算最长运⾏时间
finish_time = MPI_WTIME()
local_elapd = finish_time - start_time
call MPI_REDUCE(local_elapd, elapd, 1, MPI_REAL, MPI_MAX, 0, MPI_COMM_WORLD, ierr)
! 打印结果
if (rank == 0) then
print *, "area:", total, " elapd:", elapd
endif
! 结束
call MPI_FINALIZE(ierr)
end program main
!
生态农业技术
串⾏梯形积分法
real function trap(a, b, n, h)
implicit none
real :: a, b, n, h
real :: total
real, external :: f
real, external :: f
东溪大峡谷integer :: i
! area = h[f(a)/2+f(a+h)+f(a+2h)+...+f(a+(n-1)h)+f(b)/2]
total = (f(a) + f(b)) / 2
do i = 1, n-1
total = total + f(a+i*h)
enddo
对焦环trap = h * total
return
end function trap
! 计算函数值
real function f(x)
implicit none
real :: x
real, intrinsic :: sin, cos
春节送温暖
! y = x^2
f = x**2
return
end function f
! 获取键盘输⼊
subroutine get_input(rank, size, stat, ierr, a, b, n)
u mpi
implicit none
integer :: rank, size, stat, ierr, n, i
real :: a, b
if (rank == 0) then
print *, "Plea input the a,b,n: "
read(*, *) a, b, n
endif
! 数据⼴播
call MPI_BCAST(a, 1, MPI_REAL, 0, MPI_COMM_WORLD, ierr)
call MPI_BCAST(b, 1, MPI_REAL, 0, MPI_COMM_WORLD, ierr)
call MPI_BCAST(n, 1, MPI_INTEGER, 0, MPI_COMM_WORLD, ierr) end subroutine get_input
