2011-10-27  Richard B. Kreckel  <kreckel@ginac.de>
	    Paolo Carlini  <paolo.carlini@oracle.com>

	PR libstdc++/50880
	* include/std/complex (__complex_acosh): Fix for __z.real() < 0.
	* include/tr1/complex (__complex_acosh): Likewise.
	* testsuite/26_numerics/complex/50880.cc: New.
	* testsuite/tr1/8_c_compatibility/complex/50880.cc: Likewise.