mainverse.txt

用Fortran95写的一个矩阵求逆程序

program main
implicit none
integer :: i,j,k
integer,parameter :: N=3
real(8),dimension(3,3) :: a

    open(1000,file='matrix.dat',status='old')
        do i=1,N
            read(1000,*) a(i,:)
        end do
    close(1000)

    do k=1,N
        a(k,k) = 1.d0/a(k,k)
        do j=1,N
            if(j/=k) a(j,k) = a(k,k)*a(j,k)
        end do
        
        do i=1,N
            do j=1,N
                if(i/=k.and.j/=k) a(j,i) = a(j,i) - a(k,i)*a(j,k)
            end do
            if(i/=k) a(k,i) = -a(k,i)*a(k,k)
        end do
    end do

    do i=1,N
        write(*,'(3f12.6)') a(i,:)
    end do
        
    stop
end program