import core.math : sqrt;
import std.math.constants : PI;
import std.math.operations : isClose;

auto a = complex(2.0, 1.0);
assert(log(conj(a)) == conj(log(a)));

auto b = 2.0 * log10(complex(0.0, 1.0));
auto c = 4.0 * log10(complex(sqrt(2.0) / 2, sqrt(2.0) / 2));
assert(isClose(b, c, 0.0, 1e-15));

assert(log(complex(-1.0L, 0.0L)) == complex(0.0L, PI));
assert(log(complex(-1.0L, -0.0L)) == complex(0.0L, -PI));