Be more careful with conjugate(f(x)) -> f(conjugate(x)).

[ginac.git] / ginac / inifcns.cpp

diff --git a/ginac/inifcns.cpp b/ginac/inifcns.cpp
index 63c2d74f556d74c2c9cce124729107695a3bdf43..981e7b25f0bfda83d1d9ad542966ce4512b3ea64 100644 (file)
--- a/ginac/inifcns.cpp
+++ b/ginac/inifcns.cpp
@@ -319,8 +319,8 @@ REGISTER_FUNCTION(step, eval_func(step_eval).
                         evalf_func(step_evalf).
                         series_func(step_series).
                         conjugate_func(step_conjugate).
-                                                               real_part_func(step_real_part).
-                                                               imag_part_func(step_imag_part));
+                        real_part_func(step_real_part).
+                        imag_part_func(step_imag_part));
 
 //////////
 // Complex sign
@@ -643,10 +643,25 @@ static ex Li2_series(const ex &x, const relational &rel, int order, unsigned opt
        throw do_taylor();  // caught by function::series()
 }
 
+static ex Li2_conjugate(const ex & x)
+{
+       // conjugate(Li2(x))==Li2(conjugate(x)) unless on the branch cuts which
+       // run along the positive real axis beginning at 1.
+       if (x.info(info_flags::negative)) {
+               return Li2(x);
+       }
+       if (is_exactly_a<numeric>(x) &&
+           (!x.imag_part().is_zero() || x < *_num1_p)) {
+               return Li2(x.conjugate());
+       }
+       return conjugate_function(Li2(x)).hold();
+}
+
 REGISTER_FUNCTION(Li2, eval_func(Li2_eval).
                        evalf_func(Li2_evalf).
                        derivative_func(Li2_deriv).
                        series_func(Li2_series).
+                       conjugate_func(Li2_conjugate).
                        latex_name("\\mathrm{Li}_2"));
 
 //////////