问题描述
我想在现代 fortran（90 或更新版本）中定义一个子程序来打印矩阵（整数或实数）或向量（整数 o 数）。
SUbroUTINE print_matrix_vector( A )
! WHAT TYPE CAN I WRITE TO A ???
END SUbroUTINE
CALL print_matrix_vector( A )
独立如果 A 是实数或整数矩阵，并且 A 是实数或整数向量。
提前感谢您的评论。我认为这是很平常的事情，但我没有发现任何明确的内容。
解决方法
所以 Fortran 使用 interface 语句来声明函数的重载。我最近做了完全相同的事情。关键是创建一个接口，我调用 show 作为所有需要的单独函数的别名。
interface show
procedure show_vector_i,show_vector_r,show_vector_d
procedure show_matrix_i,show_matrix_r,show_matrix_d
end interface
这里首先是输出。
Display Matrices/Vectors
vector=
1
2
3
4
matrix=
1 5 9 13
2 6 10 14
3 7 11 15
4 8 12 16
A=
4.47723 3.36660 1.48809 -.752551
6.36660 7.19091 6.67333 5.54482
7.48809 9.67333 10.1187 9.77902
8.24745 11.5448 12.7790 13.0861
u=
6.36660
7.19091
6.67333
5.54482
v=
3.36660
7.19091
9.67333
11.5448
和代码
program FortranConsole1
use,intrinsic :: iso_fortran_env
implicit none
interface show
procedure show_matrix_i,show_matrix_d
procedure show_vector_r,show_vector_d
end interface
integer :: row(16),matrix(4,4),i
real(real64),allocatable,target :: A(:,:)
real(real64),pointer :: B(:,allocatable :: v(:),u(:)
row = [(i,i=1,16)]
matrix = reshape( row,[4,4])
print *,"Display Matrices/Vectors"
print *,""
print *,"vector="
call show(row(1:4))
print *,"matrix="
call show(matrix)
A = dble(matrix)
A = sqrt( matmul( transpose(A),A) ) - A
print *,"A="
call show(A)
v = A(:,2)
u = A(2,:)
print *,"u="
call show(u)
print *,"v="
call show(v)
contains
subroutine show_vector_i(v,w)
! Display the vector 'v' in a single column
! v : the array of real numbers
! w : the column width. default = 5
! s : sig. figures w-5 (calculated)
integer,intent(in) :: v(:)
integer,intent(in),optional :: w
integer :: i,n,wt
character(len=16) :: fmt
if(present(w)) then
wt = w
else
wt = 5
end if
n = size(v)
write( fmt,"(a,g0,a)") "(*(g",wt,".0))"
write( *,fmt ) ( v(i),new_line("A"),n )
end subroutine
subroutine show_vector_r(v,w)
! Display the vector 'v' in a single column
! v : the array of real numbers
! w : the column width. deafult = 12
! s : sig. figures w-5 (calculated)
real(real32),dg,wt
character(len=16) :: fmt
if(present(w)) then
wt = w
else
wt = 12
end if
dg = wt - 6
n = size(v)
write( fmt,a,".","))"
write( *,n )
end subroutine
subroutine show_vector_d(v,w)
! Display the vector 'v' in a single column
! v : the array of real numbers
! w : the column width. deafult = 12
! s : sig. figures w-5 (calculated)
real(real64),optional :: w
call show_vector_r(real(v),w)
end subroutine
subroutine show_matrix_i(A,w)
! Display the matrix 'A' in columns
! A : the array of integers
! w : the column width. Default = 5
integer,intent(in) :: A(:,:)
integer,j,m,wt
character(len=16) :: fmt
if(present(w)) then
wt = w
else
wt = 5
end if
n = size(A,1)
m = size(A,2)
write( fmt,".0))"
write( *,fmt ) ( (A(i,j),j=1,m),n )
end subroutine
subroutine show_matrix_r(A,w)
! Display the matrix 'A' in columns
! A : the array of real numbers
! w : the column width. deafult = 12
! s : sig. figures w-5 (calculated)
real(real32),wt
character(len=16) :: fmt
if(present(w)) then
wt = w
else
wt = 12
end if
dg = wt - 6
n = size(A,n )
end subroutine
subroutine show_matrix_d(A,w)
! Display the matrix 'A' in columns
! A : the array of dble numbers
! w : the column width. default = 12
! Converts 'A' into single precision and calls `show_matrix_r`
real(real64),optional :: w
call show_matrix_r(real(A),w)
end subroutine
end program FortranConsole1
实际上，函数应该在一个 module 文件中，以便在不同的程序中一次又一次地重用。