01 | program www_fcode_cn |
02 | implicit none |
03 | integer(2) nLbound, nUbound |
04 | real t1,t2 |
05 | call cpu_time(t1) |
06 | nLbound = 1 |
07 | nUbound = 32767 |
08 | call factorial( nLbound, nUbound ) |
09 | call cpu_time(t2) |
10 | print*, 'CPU_Time:',t2-t1 |
11 | pause |
12 | end program www_fcode_cn |
13 |
14 | subroutine factorial( nLbound, nUbound ) |
15 | Use, Intrinsic :: ISO_FORTRAN_ENV, only : OUTPUT_UNIT |
16 | implicit none |
17 | integer(2),intent(in) :: nLbound, nUbound |
18 | integer(8),parameter :: pmax = 10**13, len = 10300 |
19 | integer(8) ires(len), nL, nU |
20 | integer(8) i, j, m, n |
21 | character ch*24 |
22 |
23 | ires=0; ires(1)=1 |
24 | nL = 1; nU = 1 |
25 | do i = nLbound, nUbound |
26 | ires(nL:nU) = ires(nL:nU) * i |
27 | n = 0 |
28 | do j = nL, nU |
29 | if( ires(j)/=0 ) then |
30 | m = ires(j) / pmax |
31 | ires(j+1) = ires(j+1) + m |
32 | ires(j) = ires(j) - pmax*m |
33 | n = 1 |
34 | else if( n==0 ) then |
35 | nL = j |
36 | end if |
37 | end do |
38 | if( ires(nU+1) > 0 ) nU = nU + 1 |
39 | end do |
40 |
41 | ! 输出结果：n! |
42 | open(output_unit,file='1.txt') !输出到文件 |
43 |
44 | write(ch,*) ires(nU) |
45 | ch = adjustl(ch) |
46 | m = len_trim(ch) !首元素中整数值的位数 |
47 | n = (nU-1)*13+m-1 !指数 |
48 |
49 | !科学计数法 |
50 | write(OUTPUT_UNIT,'(a)',advance='no') ch(1:1)//'.'//ch(2:m)//'e+' |
51 | write(ch,*) n |
52 | ch = adjustl(ch) |
53 | write(OUTPUT_UNIT,'(a)') trim(ch) |
54 | !全部数字 |
55 | if( nU > 1 ) then |
56 | write(OUTPUT_UNIT,'(i<m>)',advance='no') ires(nU) |
57 | write(OUTPUT_UNIT,'(<nu-1>i13.13)') ires(nU-1:1:-1) |
58 | else |
59 | write(OUTPUT_UNIT,'(i<m>)') ires(nU) |
60 | end if |
61 | close(OUTPUT_UNIT) |
62 | end subroutine factorial |
