[空间几何] 通过3点坐标计算角度

    program angle
    implicit none
    real::x(3),y(3),z(3),angle,A,B,C,D
    integer::i,j,k

    write(*,*) 'Input the name of xyz:(e.g. a)'
    read(*,*) name
    name1=trim(name)//'.xyz'
    open(12,file=name1)
    open(13,file='result.txt')
    do i=1,3
        write(*,"(I1)") 'Input the atom number',i ,':(e.g.1)'
        read(*,*) j
        write(*,*)
        if (j==1) then
            read(12,"(11x,3(f12.6)") xi,yi,zi
        else
            do k=1,j-1
                write(*,*)
            end do
        end if
        read(12,"(11x,3(f12.6))") xi,yi,zi
        rewind(12)
    end do

    A=(x1-x2)+(y1-y2)+(z1-z2) //!first vector
    B=(x3-x2)+(y3-y2)+(z3-z2) //!second vector
    C=dsqrt((x1-x2)**2+(y1-y2)**2+(z1-z2)**2) //!quantities of first vector
    D=dsqrt((x3-x2)**2+(y3-y2)**2+(z3-z2)**2) //!quantities of second vector
    angle=acos(A*B/C/D)
    write(13,"(a,f12.4)") "The angle is:",angle/3.141592653589793238462d0*180
    end program

Program www_fcode_cn
  Implicit None
  Real(kind=kind(0.0d0))::x(3),y(3),z(3),angle,A,B,C,D
  Integer::i,k
  Character(len=30) :: cstr
  write(*,*) 'Input the name of xyz:(e.g. a)'
  read(*,*) cstr
  cstr=trim(cstr)//'.xyz'
  open(12,file=cstr)
  read(12,*)
  open(13,file='result.txt')
  do i=1,3
    read(12,*) k , cstr , x(i),y(i),z(i)    
  end do
  A=(x(1)-x(2))+(y(1)-y(2))+(z(1)-z(2)) !//!first vector
  B=(x(3)-x(2))+(y(3)-y(2))+(z(3)-z(2)) !//!second vector
  C=sqrt((x(1)-x(2))**2+(y(1)-y(2))**2+(z(1)-z(2))**2) !//!quantities of first vector
  D=sqrt((x(3)-x(2))**2+(y(3)-y(2))**2+(z(3)-z(2))**2) !//!quantities of second vector
  angle=acos(A*B/C/D)
  write(13,"(a,f12.4)") "The angle is:",angle/3.141592653589793238462d0*180
end program www_fcode_cn

Program www_fcode_cn
  Implicit None
  Real(kind=kind(0.0d0))::x(3),y(3),z(3),angle,A,B,C,D
  Integer::i,j,k
  Character(len=30) :: cstr
  write(*,*) 'Input the name of xyz:(e.g. a)'
  read(*,*) cstr
  cstr=trim(cstr)//'.xyz'
  open(12,file=cstr)
  read(12,*)
  open(13,file='result.txt')
  do i=1,3
    write(*,"(a,i1,a)") 'Input the atom number',i ,':(e.g.1)'
    read(*,*) j
    Do k = 1 , j-1
      read(12,*)
    End Do
    read(12,*) k , cstr , x(i),y(i),z(i)    
    rewind(12)
    read(12,*)
  end do
  A=(x(1)-x(2))+(y(1)-y(2))+(z(1)-z(2)) !//!first vector
  B=(x(3)-x(2))+(y(3)-y(2))+(z(3)-z(2)) !//!second vector
  C=sqrt((x(1)-x(2))**2+(y(1)-y(2))**2+(z(1)-z(2))**2) !//!quantities of first vector
  D=sqrt((x(3)-x(2))**2+(y(3)-y(2))**2+(z(3)-z(2))**2) !//!quantities of second vector
  angle=acos(A*B/C/D)
  write(13,"(a,f12.4)") "The angle is:",angle/3.141592653589793238462d0*180
end program www_fcode_cn