Compute derivative for Bessel function of first kind of order n.
Type | Intent | Optional | Attributes | Name | ||
---|---|---|---|---|---|---|
integer | :: | n |
The order of the function. |
|||
real(kind=rk), | intent(in) | :: | x |
The evaluation point. |
The function value.
function bessel_jn_derivative(n,x) result(der)
! --------------------------------------------------------------------------
!> The order of the function.
integer :: n
!> The evaluation point.
real(kind=rk), intent(in) :: x
!> The function value.
real(kind=rk) :: der
! --------------------------------------------------------------------------
! --------------------------------------------------------------------------
! Calculate the derivative by recursive relation
der = 0.5_rk*(bessel_jn(n-1,x)-bessel_jn(n+1,x))
end function bessel_jn_derivative