可能是IVF(inter visual fortran)比LF（lahey Fortran）编译器比较严格的原因

real :: A(L,M) = (/ 1,2,3,4,5,6,7,8,9,10,11,12 /)
real :: B(M,N) = (/ 1,2,3,4,5,6,7,8 /)

这种复制方式不正确，要用到reshape函数

integer :: a(2,4)=reshape([1,2,3,4,5,6,7,8],[2,4])
integer :: b(4,3)=reshape([1,2,3,4,5,6,7,8,9,10,11,12],[4,3])