Question

编译代码时，结果很奇怪（非常大，为-1.112E + 09）。当我用Matlab计算时，答案是-0.0873。

program test
real, parameter :: X11=10,X22=5,X33=5,BE1A1=2,BE1B1=2
real :: Y

call J(X11,X22,X33,BE1A1,BE1B1,M)
Y = M
print *,Y

end program test

  subroutine J(X1,X2,X3,BE1A1,BE1B1,M)

    real, intent(in) :: X1,X2,X3,BE1A1,BE1B1
    real, intent(out) :: M

    M = J1(X1,X2,X3,BE1A1,BE1B1)-J1(X1,X2,X3,BE1A1,-BE1B1)-J1(X1,X2,X3,-BE1A1,BE1B1)+J1(X1,X2,X3,-BE1A1,-BE1B1)

    contains

    real function J1(X1,X2,X3,EPS1,EPS2)

    real, intent(in) :: X1,X2,X3,EPS1,EPS2
    real :: R
    R = sqrt((X1-EPS1)**2+(X2-EPS2)**2+(X3)**2)
    J1 = log(R+X2-EPS2)

    end function J1

  end subroutine J

Answer 1

program test

real, parameter :: X11=10,X22=5,X33=5,BE1A1=2,BE1B1=2
real :: Y

call J(X11,X22,X33,BE1A1,BE1B1,CM)
Y = CM
print *,Y

end program test

  subroutine J(X1,X2,X3,BE1A1,BE1B1,CM)

    real, intent(in) :: X1,X2,X3,BE1A1,BE1B1
    real, intent(out) :: CM

    CM = J1(X1,X2,X3,BE1A1,BE1B1)-J1(X1,X2,X3,BE1A1,-BE1B1)-J1(X1,X2,X3,-BE1A1,BE1B1)+J1(X1,X2,X3,-BE1A1,-BE1B1)

    contains

    real function J1(X1,X2,X3,EPS1,EPS2)

    real, intent(in) :: X1,X2,X3,EPS1,EPS2
    real :: R
    R = sqrt((X1-EPS1)**2+(X2-EPS2)**2+(X3)**2)
    J1 = log(R+X2-EPS2)

    end function J1

  end subroutine J

现在我可以用Matlab获得相同的结果！

如何在Fortran子程序中创建函数？

1 个答案: