s13aaf

s13aaf © Numerical Algorithms Group, 2002.

Purpose

S13AAF Exponential integral E (x) 1

Synopsis

[fun_value,ifail] = s13aaf(x<,ifail>)

Description

 
 The routine calculates an approximate value for 
 
                            infty  -u
                            /     e
                     E (x)= |     -  du , x>0.
                      1     /     u  
                            x

Parameters

s13aaf

Required Input Arguments:

x                                     real

Optional Input Arguments:                       <Default>

ifail                                 integer  -1

Output Arguments:

ifail                                 integer