s21bcf calculates an approximate value for the integral
where
,
, at most one of
and
is zero, and
.
The basic algorithm, which is due to
Carlson (1979) and
Carlson (1988), is to reduce the arguments recursively towards their mean by the rule:
For
sufficiently large,
and the function may be approximated adequately by a fifth order power series
where
The truncation error in this expansion is bounded by
and the recursive process is terminated when this quantity is negligible compared with the
machine precision.
The routine may fail either because it has been called with arguments outside the domain of definition, or with arguments so extreme that there is an unavoidable danger of setting underflow or overflow.
If on entry
or
, explanatory error messages are output on the current error message unit (as defined by
x04aaf).
You should consult the
S Chapter Introduction which shows the relationship of this function to the classical definitions of the elliptic integrals.
This example simply generates a small set of nonextreme arguments which are used with the routine to produce the table of low accuracy results.
None.