+static ex log_real_part(const ex & x)
+{
+ if (x.info(info_flags::nonnegative))
+ return log(x).hold();
+ return log(abs(x));
+}
+
+static ex log_imag_part(const ex & x)
+{
+ if (x.info(info_flags::nonnegative))
+ return 0;
+ return atan2(GiNaC::imag_part(x), GiNaC::real_part(x));
+}
+
+static ex log_conjugate(const ex & x)
+{
+ // conjugate(log(x))==log(conjugate(x)) unless on the branch cut which
+ // runs along the negative real axis.
+ if (x.info(info_flags::positive)) {
+ return log(x);
+ }
+ if (is_exactly_a<numeric>(x) &&
+ !x.imag_part().is_zero()) {
+ return log(x.conjugate());
+ }
+ return conjugate_function(log(x)).hold();
+}
+