s19acf

Purpose

Synopsis

[fun_value,ifail] = s19acf(x<,ifail>)

Description

 
 This routine evaluates an approximation to the Kelvin function 
 ker x.
 
 Note: for x<0 the function is undefined and at x=0 it is infinite
 so we need only consider x>0.
 
                                                   -----      -
                                                  / (pi) -x/\/2
 For large x, ker x is asymptotically given by   /  ----e      and
                                               \/    2x        
                                                               
 this becomes so small that it cannot be computed without 
 underflow and the routine fails.
 

Parameters

s19acf

Required Input Arguments:

x                                     real

Optional Input Arguments:                       <Default>

ifail                                 integer  -1

Output Arguments:

ifail                                 integer