Nicer output for factorial().

[ginac.git] / ginac / inifcns.cpp

diff --git a/ginac/inifcns.cpp b/ginac/inifcns.cpp
index fa5e9a20fb4e2f0aff9fea5d09663bf38d709f2a..ad4e035aaf6d793904e63d641654962508af2b78 100644 (file)
--- a/ginac/inifcns.cpp
+++ b/ginac/inifcns.cpp
@@ -3,7 +3,7 @@
  *  Implementation of GiNaC's initially known functions. */
 
 /*
- *  GiNaC Copyright (C) 1999-2004 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2005 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
@@ -67,10 +67,10 @@ static ex conjugate_conjugate(const ex & arg)
 }
 
 REGISTER_FUNCTION(conjugate_function, eval_func(conjugate_eval).
-                       evalf_func(conjugate_evalf).
-                       print_func<print_latex>(conjugate_print_latex).
-                       conjugate_func(conjugate_conjugate).
-                       set_name("conjugate","conjugate"));
+                                      evalf_func(conjugate_evalf).
+                                      print_func<print_latex>(conjugate_print_latex).
+                                      conjugate_func(conjugate_conjugate).
+                                      set_name("conjugate","conjugate"));
 
 //////////
 // absolute value
@@ -467,6 +467,17 @@ static ex factorial_eval(const ex & x)
                return factorial(x).hold();
 }
 
+static void factorial_print_dflt_latex(const ex & x, const print_context & c)
+{
+       if (is_exactly_a<symbol>(x) ||
+           is_exactly_a<constant>(x) ||
+               is_exactly_a<function>(x)) {
+               x.print(c); c.s << "!";
+       } else {
+               c.s << "("; x.print(c); c.s << ")!";
+       }
+}
+
 static ex factorial_conjugate(const ex & x)
 {
        return factorial(x);
@@ -474,6 +485,8 @@ static ex factorial_conjugate(const ex & x)
 
 REGISTER_FUNCTION(factorial, eval_func(factorial_eval).
                              evalf_func(factorial_evalf).
+                             print_func<print_dflt>(factorial_print_dflt_latex).
+                             print_func<print_latex>(factorial_print_dflt_latex).
                              conjugate_func(factorial_conjugate));
 
 //////////
@@ -485,11 +498,32 @@ static ex binomial_evalf(const ex & x, const ex & y)
        return binomial(x, y).hold();
 }
 
+static ex binomial_sym(const ex & x, const numeric & y)
+{
+       if (y.is_integer()) {
+               if (y.is_nonneg_integer()) {
+                       const unsigned N = y.to_int();
+                       if (N == 0) return _num0;
+                       if (N == 1) return x;
+                       ex t = x.expand();
+                       for (unsigned i = 2; i <= N; ++i)
+                               t = (t * (x + i - y - 1)).expand() / i;
+                       return t;
+               } else
+                       return _num0;
+       }
+
+       return binomial(x, y).hold();
+}
+
 static ex binomial_eval(const ex & x, const ex &y)
 {
-       if (is_exactly_a<numeric>(x) && is_exactly_a<numeric>(y))
-               return binomial(ex_to<numeric>(x), ex_to<numeric>(y));
-       else
+       if (is_exactly_a<numeric>(y)) {
+               if (is_exactly_a<numeric>(x) && ex_to<numeric>(x).is_integer())
+                       return binomial(ex_to<numeric>(x), ex_to<numeric>(y));
+               else
+                       return binomial_sym(x, ex_to<numeric>(y));
+       } else
                return binomial(x, y).hold();
 }