1 /** @file inifcns_zeta.cpp
3 * Implementation of the Zeta-function and some related stuff. */
6 * GiNaC Copyright (C) 1999 Johannes Gutenberg University Mainz, Germany
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
33 #ifndef NO_GINAC_NAMESPACE
35 #endif // ndef NO_GINAC_NAMESPACE
38 // Riemann's Zeta-function
41 static ex zeta1_evalf(ex const & x)
45 END_TYPECHECK(zeta(x))
47 return zeta(ex_to_numeric(x));
50 static ex zeta1_eval(ex const & x)
52 if (x.info(info_flags::numeric)) {
53 numeric y = ex_to_numeric(x);
54 // trap integer arguments:
58 if (x.is_equal(exONE()))
59 throw(std::domain_error("zeta(1): infinity"));
60 if (x.info(info_flags::posint)) {
61 if (x.info(info_flags::odd))
62 return zeta(x).hold();
64 return abs(bernoulli(y))*pow(Pi,x)*numTWO().power(y-numONE())/factorial(y);
66 if (x.info(info_flags::odd))
67 return -bernoulli(numONE()-y)/(numONE()-y);
73 return zeta(x).hold();
76 static ex zeta1_diff(ex const & x, unsigned diff_param)
78 GINAC_ASSERT(diff_param==0);
80 return zeta(exONE(), x);
83 const unsigned function_index_zeta1 = function::register_new("zeta", zeta1_eval, zeta1_evalf, zeta1_diff, NULL);
86 // Derivatives of Riemann's Zeta-function zeta(0,x)==zeta(x)
89 static ex zeta2_eval(ex const & n, ex const & x)
91 if (n.info(info_flags::numeric)) {
92 // zeta(0,x) -> zeta(x)
97 return zeta(n, x).hold();
100 static ex zeta2_diff(ex const & n, ex const & x, unsigned diff_param)
102 GINAC_ASSERT(diff_param<2);
106 throw(std::logic_error("cannot diff zeta(n,x) with respect to n"));
112 const unsigned function_index_zeta2 = function::register_new("zeta", zeta2_eval, NULL, zeta2_diff, NULL);
114 #ifndef NO_GINAC_NAMESPACE
116 #endif // ndef NO_GINAC_NAMESPACE