When I ran the following simple program
program test
! integer m,n,r,i
double precision x(2),y(3),z(4)
x=(/2.0,1.0/)
y=(/1.0,2.0,1.0/)
call polymul(x,2,y,3,z,4)
print *,z
end
subroutine polymul(x,m,y,n,z,r)
! polynominal multipy
integer i,j,k
do i=1,r
z(i)=0.0
end do
do i=1,m
do j=1,n
k=i+j-1
z(k)=z(k)+x(i)*y(j)
end do
end do
end
it showed
Error: Unclassifiable statement
You have not declared what x, y, and z are in the subroutine. Fortran does not know if these variables are functions (that have not been defined) or an array. The fix is simple: declare the arrays explicitly in the subroutine:
subroutine polymul(x, m, y, n, z, r)
implicit none
integer m, n, r
double precision x(m), y(n), z(r)
integer i, j, k
do i=1,r
z(i)=0.0
enddo
do i=1,m
do j=1,n
k=i+j-1
z(k)=z(k)+x(i)*y(j)
enddo
enddo
end subroutine
Just as ifort prompts that （variable z）This name has not been declared as an array or a function.u need to declare variable x,y,z to be arrays in subroutine polymul.
Related
I'm writing a code for LU decomposition and I don't know how to fix the "unexpected data declaration statement" pointed at line 8 (where I'm declaring an array. See the code fragment). Why is it unexpected?
!Decomposição LU
!-----------------------------------------------------------
PROGRAM LUdecomp
IMPLICIT INTEGER (I-K,N), REAL (A-H, L-M,O-Z)
INTEGER, PARAMETER :: N=3
REAL, DIMENSION (N,N) :: A,L,U
A = reshape((/3.,1.,4.,4.,2.,0.,3.,2.,3./),(/3,3/)) !exemplo do Bortoli*******
REAL, DIMENSION(3) :: B=(/9.,3.,-2./),Z,X
OPEN(1,file = 'LUFACTOR.out')
!
! FORALL (I = 1:N, J = 1:N) A(I,J) = 1.0/REAL(I+J-1)
!-------Fazendo a fatoração A = LU-----------------------------
CALL LU(N, A, L, U)
DO I=1,N
WRITE(*,10)(L(I,J), J=1,N), (U(I,J), J=1,N)
END DO
10 FORMAT(3(F8.4), 7x, 3(F8.4))
!
This statement
REAL, DIMENSION(3) :: B=(/9.,3.,-2./),Z,X
is in the wrong place. In a Fortran program-unit (program, subroutine, function) -- certainly one without the new ASSOCIATE and BLOCK constructs -- all declarations have to precede all executable statements.
Move the misplaced statement ahead of the first executable statement.
I kindly request your help on this code where I kept on getting
an error: Rank mismatch in array reference at (1) (2/1). My objective is to go through each point in a cube(p = i+(j-1)*N + (k-1)NN) and calculate the gradient of the potential along each axis (gradphi_x, gradphi_y, gradphi_z).
PROGRAM sub_rho_phi
integer, parameter:: N=3
real, dimension(N):: gradphi_x, gradphi_y, gradphi_z
call output(gradphi_x, gradphi_y, gradphi_z)
open(unit=1,file="grad_phi.dat")
l = 0
do
l=l+1
write(1,*) gradphi_x(l),gradphi_y(l),gradphi_z(l)
if ( l == N**3) then
exit
end if
end do
END
SUBROUTINE output( gradphi_x, gradphi_y, gradphi_z )
real, parameter:: h=0.7,G=6.67,M=1.98892*(10**3)!!in(10**15) kg
integer, parameter:: N=3
real, dimension(N):: r, gradphi_x,gradphi_y,gradphi_z
integer, dimension(N**3):: x,y,z
integer:: p
real:: a
a=500/h !in kpc
do i=0, N
do j=0, N
do k=0, N
p = i+(j-1)*N + (k-1)*N*N
x(p,1)=i
y(p,2)=j
z(p,3)=k
r(p)=sqrt(x(p,1)*x(p,1)+y(p,2)*y(p,2)+z(p,3)*z(p,3))
gradphi_x(p)=(G*M)*x(p,1)/r(p)*(r(p)+a)**2
gradphi_y(p)=(G*M)*y(p,2)/r(p)*(r(p)+a)**2
gradphi_z(p)=(G*M)*z(p,3)/r(p)*(r(p)+a)**2
enddo
enddo
enddo
return
END
You have declared x, y and z as one dimensional arrays, but are using two dimensional indexing all the way through output.
I am a very new user to Fortran 90. I am learning how to program. Currently, I am trying to create a program to do matrix multiplication. But, I am getting an error.
Program Matrix_Multiplication
Implicit None
Real, Dimension(2:2) :: A, B, C
Integer :: i, j, k
A = 0.0
B = 0.0
C = 0.0
do i = 1, 2
do j = 1, 2
Read (80, *) A
Read (90, *) B
Write (100, *) A, B
end do
end do
Call subC(A, B, C)
Write (110, *) C
End Program Matrix_Multiplication
Subroutine subC(A, B, C)
Implicit None
Real, Intent(IN) :: A, B
Integer :: i, j, k
Real, Intent(OUT) :: C
do i = 1, 2
do j = 1, 2
C = C(i, j) + (A(i, j)*B(j, i))
end do
end do
return
End Subroutine
On compiling:
C(i, j) = (A(i, k)*B(k, j)) 1 Error: Unclassifiable statement at (1)
As francescalus stated in his comment, A, B, and C are declared as scalars inside the subroutine. Therefore, you cannot index them as arrays.
In this particular case I would rather use the intrinsic function matmul instead of writing your own matrix-matrix multiplication:
Program Matrix_Multiplication
Implicit None
Real, Dimension (2,2) :: A,B,C
A=0.0
B=0.0
C=0.0
do i=1,2
do j=1,2
Read (80,*) A(j,i)
Read (90,*) B(j,i)
Write (100,*) A,B
end do
end do
C = matmul(A,B)
Write (110,*) C
End Program Matrix_Multiplication
For larger matrices there are highly optimized math-libraries out there. Using BLAS/LAPACK is highly recommended then. The correct subroutine for your example would be SGEMM.
More of a formatted comment than an answer but the declaration
Real, Dimension (2:2) :: A,B,C
declares A,B and C to be rank-1 arrays of 0 elements. You probably ought to rewrite the statement as
Real, Dimension (2,2) :: A,B,C
which declares the arrays to be rank-2 and 2x2.
I'm writing a code for LU decomposition and I don't know how to fix the "unexpected data declaration statement" pointed at line 8 (where I'm declaring an array. See the code fragment). Why is it unexpected?
!Decomposição LU
!-----------------------------------------------------------
PROGRAM LUdecomp
IMPLICIT INTEGER (I-K,N), REAL (A-H, L-M,O-Z)
INTEGER, PARAMETER :: N=3
REAL, DIMENSION (N,N) :: A,L,U
A = reshape((/3.,1.,4.,4.,2.,0.,3.,2.,3./),(/3,3/)) !exemplo do Bortoli*******
REAL, DIMENSION(3) :: B=(/9.,3.,-2./),Z,X
OPEN(1,file = 'LUFACTOR.out')
!
! FORALL (I = 1:N, J = 1:N) A(I,J) = 1.0/REAL(I+J-1)
!-------Fazendo a fatoração A = LU-----------------------------
CALL LU(N, A, L, U)
DO I=1,N
WRITE(*,10)(L(I,J), J=1,N), (U(I,J), J=1,N)
END DO
10 FORMAT(3(F8.4), 7x, 3(F8.4))
!
This statement
REAL, DIMENSION(3) :: B=(/9.,3.,-2./),Z,X
is in the wrong place. In a Fortran program-unit (program, subroutine, function) -- certainly one without the new ASSOCIATE and BLOCK constructs -- all declarations have to precede all executable statements.
Move the misplaced statement ahead of the first executable statement.
I kindly request your help on this code where I kept on getting
an error: Rank mismatch in array reference at (1) (2/1). My objective is to go through each point in a cube(p = i+(j-1)*N + (k-1)NN) and calculate the gradient of the potential along each axis (gradphi_x, gradphi_y, gradphi_z).
PROGRAM sub_rho_phi
integer, parameter:: N=3
real, dimension(N):: gradphi_x, gradphi_y, gradphi_z
call output(gradphi_x, gradphi_y, gradphi_z)
open(unit=1,file="grad_phi.dat")
l = 0
do
l=l+1
write(1,*) gradphi_x(l),gradphi_y(l),gradphi_z(l)
if ( l == N**3) then
exit
end if
end do
END
SUBROUTINE output( gradphi_x, gradphi_y, gradphi_z )
real, parameter:: h=0.7,G=6.67,M=1.98892*(10**3)!!in(10**15) kg
integer, parameter:: N=3
real, dimension(N):: r, gradphi_x,gradphi_y,gradphi_z
integer, dimension(N**3):: x,y,z
integer:: p
real:: a
a=500/h !in kpc
do i=0, N
do j=0, N
do k=0, N
p = i+(j-1)*N + (k-1)*N*N
x(p,1)=i
y(p,2)=j
z(p,3)=k
r(p)=sqrt(x(p,1)*x(p,1)+y(p,2)*y(p,2)+z(p,3)*z(p,3))
gradphi_x(p)=(G*M)*x(p,1)/r(p)*(r(p)+a)**2
gradphi_y(p)=(G*M)*y(p,2)/r(p)*(r(p)+a)**2
gradphi_z(p)=(G*M)*z(p,3)/r(p)*(r(p)+a)**2
enddo
enddo
enddo
return
END
You have declared x, y and z as one dimensional arrays, but are using two dimensional indexing all the way through output.