ei Function

public function ei(x)

Exponential integral .

Arguments

Type IntentOptional Attributes Name
real(kind=wp), intent(in) :: x

Return Value real(kind=wp)


Calls

proc~~ei~~CallsGraph proc~ei ei proc~dei dei proc~ei->proc~dei proc~ninf ninf proc~ei->proc~ninf proc~pinf pinf proc~ei->proc~pinf

Source Code

  real(wp) function ei(x)
    !! Exponential integral \(\mathrm{Ei}(x)\).
    !
    !! \(\lbrace x \in \mathbb{R} \mid x \neq 0 \rbrace\)

    real(wp), intent(in) :: x

    if (x == 0.0_wp) then
      ei = ninf()
    else if (x < -738.0_wp) then
      ei = 0.0_wp
    else if (x <= 709.0_wp) then
      ei = dei(x)
    else
      ei = pinf()
    end if
  end function ei