program average_temperature
implicit none
integer, parameter :: num_locations = 100
integer, parameter :: num_times = 24
integer, parameter :: num_heights = 10
real :: temperature(num_locations, num_times, num_heights)
real :: average_temp
integer :: location_index
integer :: i, j
! 初始化温度数据,这里只是示例,实际可能从文件等读取
do i = 1, num_locations
do j = 1, num_times
temperature(i, j, :) = real(i + j)
end do
end do
location_index = 5! 假设计算第5个地点的平均温度
average_temp = sum(temperature(location_index, :, :)) / (num_times * num_heights)
print *, 'The average temperature at location ', location_index,'is: ', average_temp
end program average_temperature
代码优化以提高计算效率:
- 减少内存访问:Fortran 中数组是按列优先存储的,在进行求和操作时,尽量让内层循环遍历变化最快的维度,这样可以减少内存的随机访问,提高缓存命中率。例如,将求和循环改写为按照列优先的顺序访问。
average_temp = 0.0
do j = 1, num_heights
do i = 1, num_times
average_temp = average_temp + temperature(location_index, i, j)
end do
end do
average_temp = average_temp / (num_times * num_heights)
- 并行计算:使用 OpenMP 等并行框架,在多核处理器上并行计算平均温度。如果
num_times
和 num_heights
比较大,并行计算可以显著提高效率。例如:
program average_temperature
use omp_lib
implicit none
integer, parameter :: num_locations = 100
integer, parameter :: num_times = 24
integer, parameter :: num_heights = 10
real :: temperature(num_locations, num_times, num_heights)
real :: average_temp
integer :: location_index
integer :: i, j
! 初始化温度数据,这里只是示例,实际可能从文件等读取
do i = 1, num_locations
do j = 1, num_times
temperature(i, j, :) = real(i + j)
end do
end do
location_index = 5! 假设计算第5个地点的平均温度
average_temp = 0.0
!$omp parallel do reduction(+:average_temp)
do j = 1, num_heights
do i = 1, num_times
average_temp = average_temp + temperature(location_index, i, j)
end do
end do
!$omp end parallel do
average_temp = average_temp / (num_times * num_heights)
print *, 'The average temperature at location ', location_index,'is: ', average_temp
end program average_temperature
- 数据类型选择:如果数据的精度要求不高,可以使用
real(4)
(单精度浮点数)代替默认的 real(8)
(双精度浮点数),这样可以减少内存占用和计算时间。但要注意单精度浮点数的精度问题,可能会导致结果不准确。
- 避免不必要的计算:在实际应用中,如果某些数据是不变的或者已经计算过的,尽量避免重复计算。例如,如果平均温度的计算是基于一些预处理后的数据,确保预处理过程没有不必要的重复操作。