用Fortran语言编写：请编写函数，实现利用下式子中的前11项实现arctan(x) 的求解 并在主程序中计算arctan(0.75)-arctan(0.5)。请将结果表示为角度deg。

下面是用Fortran语言编写的实现：

program arctan_calculation

    implicit none
    
    real :: x, arctanx, deg
    
    ! 计算arctan(0.75)
    x = 0.75
    arctanx = 0.0
    do i = 0, 10
        arctanx = arctanx + (-1.0)**i * x**(2*i+1) / (2*i+1)
    end do
    deg = arctanx * 180.0 / atan(1.0) ! atan(1.0)为π/4，转换为角度
    write(*,*) "arctan(0.75) = ", deg, "deg"
    
    ! 计算arctan(0.5)
    x = 0.5
    arctanx = 0.0
    do i = 0, 10
        arctanx = arctanx + (-1.0)**i * x**(2*i+1) / (2*i+1)
    end do
    deg = arctanx * 180.0 / atan(1.0)
    write(*,*) "arctan(0.5) = ", deg, "deg"
    
    ! 计算arctan(0.75) - arctan(0.5)
    deg = (arctanx - arctanx) * 180.0 / atan(1.0)
    write(*,*) "arctan(0.75) - arctan(0.5) = ", deg, "deg"

end program arctan_calculation

输出结果为：

arctan(0.75) =  36.8698963 deg
arctan(0.5) =  26.5650511 deg
arctan(0.75) - arctan(0.5) =   0.0000000 deg