# §6.21(i) Introduction

In this section we provide links to the research literature describing the implementation of algorithms in software for the evaluation of functions described in this chapter. Citations in bulleted lists refer to papers for which research software has been made available and can be downloaded via the Web. References to research software that is available in other ways is listed separately.

A more complete list of available software for computing these functions is found in the Software Index. For another listing of Web-accessible software for the functions in this chapter, see GAMS Class C5.

# §6.21(ii) $\mathop{E_{1}\/}\nolimits\!\left(x\right)$, $\mathop{\mathrm{Ei}\/}\nolimits\!\left(x\right)$, $\mathop{\mathrm{Si}\/}\nolimits\!\left(x\right)$, $\mathop{\mathrm{Ci}\/}\nolimits\!\left(x\right)$, $\mathop{\mathrm{Shi}\/}\nolimits\!\left(x\right)$, $\mathop{\mathrm{Chi}\/}\nolimits\!\left(x\right)$, $x\in\Real$

• Amos (1980a). Fortran.

• Cody (1993b). Fortran.

• Smith (2011). Fortran.

See also Gautschi (1973), MacLeod (1996b), Paciorek (1970), and Stegun and Zucker (1976).

# §6.21(iii) $\mathop{E_{1}\/}\nolimits\!\left(z\right)$, $\mathop{\mathrm{Si}\/}\nolimits\!\left(z\right)$, $\mathop{\mathrm{Ci}\/}\nolimits\!\left(z\right)$, $\mathop{\mathrm{Shi}\/}\nolimits\!\left(z\right)$, $\mathop{\mathrm{Chi}\/}\nolimits\!\left(z\right)$, $z\in\Complex$

• Amos (1990). Fortran.