问题
I was going through all the other threads about undefined reference and I was unable to figure out why this piece of codes is not working. I am basically trying to run a function from a module into a subroutine in the main program. But I keep getting an error
Main:
program main
use m1
implicit none
integer, dimension(:,:), allocatable :: A,AFun
integer :: n,i,j
print *, "enter value for n"
read *, n
do i=1,n
do j=1,n
A(i,j)=i**2-j**3
end do
end do
print *, "Matrix A: "
call prMat(A,n)
call matFun(A,AFun,n)
print *, "Matrix AFun:"
call prMat(AFun,n)
call fromAvg(AFun,n)
contains
subroutine prMat(x,n)
implicit none
integer, dimension(n,n) :: x
integer :: i,j,n
do i=1,n
write(*,*), (x(i,j))
end do
end subroutine prMat
subroutine matfun(x,y,n)
implicit none
integer, dimension(n,n) :: x,y
integer :: i,j,n,f1
do i = 1,n
do j=1,n
y(i,j)=f1(x,i,j,n)
end do
end do
end subroutine matFun
subroutine fromAvg(x,n)
integer, dimension(:,:) :: x
integer :: i,j,n
integer :: s,avg,g,b
s=0; g=0; b=0
do i=1,n
do j=1,n
s=s+x(i,j)
end do
end do
avg=s/(n*n)
do i = 1,n
do j = 1,n
if ( x(i,j) > avg ) then
g = g + 1
else
b = b + 1
end if
end do
end do
print *, "In from avg, average=", avg
print *, "Number of values greater than average is ",g
print *, "Number of values less than average is ",b
end subroutine fromAvg
integer, dimension(:,:), allocatable, intent(IN) :: x
integer :: i,j,n
integer :: s,avg,g,b
s=0; g=0; b=0
do i=1,n
do j=1,n
s=s+x(i,j)
end do
end do
avg=s/(n*n)
do i = 1,n
do j = 1,n
if ( x(i,j) > avg ) then
g = g + 1
elseif ( x(i,j) < avg ) then
b = b + 1
end if
end do
end do
print *, "In from avg, average=", avg
print *, "Number of values greater than average is ",g
print *, "Number of values less than average is ",b
end subroutine fromAvg
end program main
Module Function:
module m1
implicit none
private
public :: f1
contains
function f1(x,p,q,n)
integer, dimension(:,:) :: x
integer, intent(in) :: p,q,n
integer :: i,f1
f1=0
do i = 1,n
f1 = f1 + x(p,n)
end do
do i = 1,n
f1 = f1 + x(n,q)
end do
end function f1
end module m1
The error that I keep getting is as follows:
/tmp/ccKZHw7L.o: In function `matfun.1520':
lab4_b.f90:(.text+0x808): undefined reference to `__m1_MOD_f1'
collect2: ld returned 1 exit status
Am I missing something? I have use m1 in the beginning of my main program before the implicit none statement.
回答1:
In the subroutine matfun f1 is (re-)declared to be an integer, in the line
integer :: i,j,n,f1
This effectively masks the module function from sight. Since the code is (correctly) using the module containing f1 it shouldn't also be declared inside the subroutine.
Then my compiler complains that there is no definition for fromavg but I guess you know that.
来源：https://stackoverflow.com/questions/40883296/undefined-reference-to-a-function-in-a-module