| Author(s): K.S. Kölbig | Library: MATHLIB |
| Submitter: | Submitted: 07.06.1992 |
| Language: Fortran | Revised: |
Function subprograms RRIZET and DRIZET calculate the Riemann zeta function
for real arguments 
, where 
is defined by analytic
continuation for x < 1. For x = 1, 
has a pole of order
one.
On CDC and Cray computers, the double-precision version DRIZET is not available.
Structure:
FUNCTION subprograms
User Entry Names: RRIZET, DRIZET
Files Referenced: Unit 6
External References: GAMMA, DGAMMA,
MTLMTR, ABEND
Usage:
In any arithmetic expression,
RRIZET(X) or DRIZET(X)
if 
, and
if 
,
where RRIZET is of type REAL, DRIZET is of type
DOUBLE PRECISION, and where X has the same type as the
function name.
Method:
Rational Chebyshev approximation. For 
the
reflection formula for 
is used.
Accuracy:
RRIZET (except on CDC and Cray computers) has full single-precision accuracy. For most values of the argument X, DRIZET (and RRIZET on CDC and Cray computers) has an accuracy of approximately one significant digit less than the machine precision.
Error handling:
Error C315.1: 
. The function value is set
to zero, and a message is written on Unit 6,
unless subroutine MTLSET (N002) has been called.
References:
