- Macro GINAC_CHECK_LIBCLN only checks if doublefactorial is available now.

[ginac.git] / ginac / inifcns_zeta.cpp

diff --git a/ginac/inifcns_zeta.cpp b/ginac/inifcns_zeta.cpp
index e343b6fbe2692dc6c2eb92953309b65c0e2ec081..4be6f0226cae4f35f983c89f071a8f5afd1414a9 100644 (file)
--- a/ginac/inifcns_zeta.cpp
+++ b/ginac/inifcns_zeta.cpp
@@ -3,7 +3,7 @@
  *  Implementation of the Zeta-function and some related stuff. */
 
 /*
- *  GiNaC Copyright (C) 1999 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2000 Johannes Gutenberg University Mainz, Germany
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -29,6 +29,7 @@
 #include "numeric.h"
 #include "power.h"
 #include "symbol.h"
+#include "utils.h"
 
 #ifndef NO_GINAC_NAMESPACE
 namespace GiNaC {
@@ -38,42 +39,78 @@ namespace GiNaC {
 // Riemann's Zeta-function
 //////////
 
-static ex zeta_eval(ex const & x)
+static ex zeta1_evalf(const ex & x)
+{
+    BEGIN_TYPECHECK
+        TYPECHECK(x,numeric)
+    END_TYPECHECK(zeta(x))
+        
+    return zeta(ex_to_numeric(x));
+}
+
+static ex zeta1_eval(const ex & x)
 {
     if (x.info(info_flags::numeric)) {
         numeric y = ex_to_numeric(x);
         // trap integer arguments:
         if (y.is_integer()) {
             if (y.is_zero())
-                return -exHALF();
-            if (x.is_equal(exONE()))
+                return -_ex1_2();
+            if (x.is_equal(_ex1()))
                 throw(std::domain_error("zeta(1): infinity"));
             if (x.info(info_flags::posint)) {
                 if (x.info(info_flags::odd))
                     return zeta(x).hold();
                 else
-                    return abs(bernoulli(y))*pow(Pi,x)*numTWO().power(y-numONE())/factorial(y);
+                    return abs(bernoulli(y))*pow(Pi,x)*pow(_num2(),y-_num1())/factorial(y);
             } else {
                 if (x.info(info_flags::odd))
-                    return -bernoulli(numONE()-y)/(numONE()-y);
+                    return -bernoulli(_num1()-y)/(_num1()-y);
                 else
-                    return numZERO();
+                    return _num0();
             }
         }
     }
     return zeta(x).hold();
 }
 
-static ex zeta_evalf(ex const & x)
+static ex zeta1_diff(const ex & x, unsigned diff_param)
 {
-    BEGIN_TYPECHECK
-        TYPECHECK(x,numeric)
-    END_TYPECHECK(zeta(x))
+    GINAC_ASSERT(diff_param==0);
     
-    return zeta(ex_to_numeric(x));
+    return zeta(_ex1(), x);
+}
+
+const unsigned function_index_zeta1 = function::register_new("zeta", zeta1_eval, zeta1_evalf, zeta1_diff, NULL);
+
+//////////
+// Derivatives of Riemann's Zeta-function  zeta(0,x)==zeta(x)
+//////////
+
+static ex zeta2_eval(const ex & n, const ex & x)
+{
+    if (n.info(info_flags::numeric)) {
+        // zeta(0,x) -> zeta(x)
+        if (n.is_zero())
+            return zeta(x);
+    }
+    
+    return zeta(n, x).hold();
+}
+
+static ex zeta2_diff(const ex & n, const ex & x, unsigned diff_param)
+{
+    GINAC_ASSERT(diff_param<2);
+    
+    if (diff_param==0) {
+        // d/dn zeta(n,x)
+        throw(std::logic_error("cannot diff zeta(n,x) with respect to n"));
+    }
+    // d/dx psi(n,x)
+    return zeta(n+1,x);
 }
 
-REGISTER_FUNCTION(zeta, zeta_eval, zeta_evalf, NULL, NULL);
+const unsigned function_index_zeta2 = function::register_new("zeta", zeta2_eval, NULL, zeta2_diff, NULL);
 
 #ifndef NO_GINAC_NAMESPACE
 } // namespace GiNaC