s21baf

Purpose

Synopsis

[fun_value,ifail] = s21baf(x,y<,ifail>)

Description

 
 This routine calculates an approximate value for the integral
 
                               infty
                             1 /         dt
                    R (x,y)= - |     ----------
                     C       2 /       ___
                               0     \/t+x(t+y)
 
 where x>=0 and y/=0.
 
 This function, which is related to the logarithm or inverse 
 hyperbolic functions for y<x and to inverse circular functions if
 x<y, arises as a degenerate form of the elliptic integral of the 
 first kind. If y<0, the result computed is the Cauchy principal 
 value of the integral.
 
 Within the domain of definition, the function value is itself 
 representable for all representable values of its arguments. 
 However, for values of the arguments near the extremes the above 
 algorithm must be modified so as to avoid causing underflows or 
 overflows in intermediate steps. In extreme regions arguments are
 pre-scaled away from the extremes and compensating scaling of the
 result is done before returning to the calling program.
 

Parameters

s21baf

Required Input Arguments:

x                                     real
y                                     real

Optional Input Arguments:                       <Default>

ifail                                 integer  -1

Output Arguments:

ifail                                 integer