我正在开发一个有趣的小矩阵计算器程序来完善我的 Fortran，但我遇到了一些问题。除了乘法和转置之外，一切都运行良好。当我乘以时，我得到的答案是完全错误的，我不确定为什么会这样。例如：如果我乘
| 1 2 3 | | 1 2 |
| 4 5 6 | * | 3 4 |
| 5 6 |
I get | 26 32 |
| 10 16 |
but wolframalpha says I should be getting
| 22 28 |
| 49 64 |
另外，至于转置，如果我尝试转置
| 1 2 3 |
| 4 5 6 |
| 7 8 9 |,
I get
| 1 2 3 |
| 4 5 6 |
| 7 8 9 |
而不是它应该是什么。
下面是我的整个程序，因此您可以自己编译它并查看问题所在。我怀疑问题在于输出、乘法和转置子例程。
PROGRAM G6P5
integer :: r1,r2,c1,c2,i,j,k,s
real :: input
real, dimension (11,11) :: mat1, mat2, rmat
write (*,*) 'Please make a selection:'
write (*,*) 'Enter 1 to add matrices'
write (*,*) 'Enter 2 to subtract matrices'
write (*,*) 'Enter 3 to multiply matrices'
write (*,*) 'Enter 4 to transpose a matrix'
write (*,*) 'Enter 5 to quit'
read *, s
select case (s)
case (1)
print *, 'Enter # of rows & columns (1-10) (ex. 3 3 = 3x3)'
read *, r1,c1
print *, 'Matrix 1:'
call fillmatrix(r1,c1,mat1)
r2 = r1
c2 = c1
print *, 'Matrix 2:'
call fillmatrix(r2,c2,mat2)
call output(r1,c1,mat1,'Matrix 1: ')
call output(r2,c2,mat2,'Matrix 2: ')
rmat = mat1+mat2
call output(r1,c1,rmat,'Sum: ')
case (2)
print *, 'Enter # of rows & columns (1-10) (ex. 3 3 = 3x3)'
read *, r1,c1
print *, 'Matrix 1:'
call fillmatrix(r1,c1,mat1)
r2 = r1
c2 = c1
print *, 'Matrix 2:'
call fillmatrix(r2,c2,mat2)
rmat = mat1-mat2
call output(r1,c1,mat1,'Matrix 1: ')
call output(r2,c2,mat2,'Matrix 2: ')
call output(r1,c1,rmat,'Sum: ')
case (3)
print *, 'Enter # of rows & columns for matrix 1'
print *, '(1 through 10, ex: 3 3 = 3x3)'
read *, r1,c1
print *, 'Matrix 1:'
call fillmatrix(r1,c1,mat1)
print *, 'Enter # of rows & columns for matrix 2'
print *, '(1 through 10, ex: 3 3 = 3x3)'
read *, r2,c2
print *, 'Matrix 2:'
call fillmatrix(r2,c2,mat2)
if (c1.eq.r2) then
call multiply(mat1,mat2,rmat,r1,r2,c1,c2)
call output(r1,c1,mat1,'Matrix 1: ')
call output(r2,c2,mat2,'Matrix 2: ')
call output(r1,c2,rmat,'Product: ')
end if
case (4)
print *, 'Enter # of rows & columns for matrix 1'
print *, '(1 through 10, ex: 3 3 = 3x3)'
read *, r1,c1
print *, 'Matrix 1:'
call fillmatrix(r1,c1,mat1)
call transpose(mat1,rmat,r1,c1)
call output(r1,c1,rmat,'Transpose:')
case (5)
print *,'5'
case default
print *,'default'
end select
! call fillmatrix(rows,columns,mat1)
! write (*,*) matrix1
END PROGRAM
subroutine fillmatrix(r,c,matrix)
integer, intent(in) :: r
integer, intent(in):: c
real, intent(out), dimension(r,c) :: matrix
integer i,j
do i=1,r
do j = 1,c
write (*,'(A,I2,A,I2,A)') 'Enter value (',i,',',j,').'
read*, matrix(i,j)
enddo
enddo
end subroutine
subroutine multiply(m1,m2,res,row1,row2,col1,col2)
integer, intent(in) :: row1,row2,col1,col2
real, intent(in), dimension(row1,col1) :: m1
real, intent(in), dimension(row2,col2) :: m2
real, intent(out), dimension(row1,col2) :: res
integer :: i,j,k
do i = 1, col2
do j = 1, col1
res(j, i) = 0
enddo
do j = 1, col1
do k = 1, row1
res(k, i) = res(k, i) + m1(k, j)*m2(j, i)
enddo
enddo
enddo
end subroutine
subroutine transpose(m1,res,row,col)
integer, intent(in) :: row,col
real, intent(in), dimension(row,col) :: m1
real, intent(out), dimension(row,col) :: res
integer :: i,j,k
do i = 1,col
do j = 1,row
res(i,j) = m1(j,i)
enddo
enddo
end subroutine
subroutine output(r,c,matrix,name)
integer, intent(in) :: r
integer, intent(in):: c
character(len=10) :: name
real, intent(out), dimension(3,3) :: matrix
integer i,j
print *,name
do i = 1, r
write(*,"(100F6.1)") ( matrix(i,j), j=1,c )
enddo
end subroutine