1 files changed, 12 insertions, 0 deletions
diff --git a/src/complex/cacosh.c b/src/complex/cacosh.c
new file mode 100644
index 0000000..76127f7
--- /dev/null
+++ b/src/complex/cacosh.c
@@ -0,0 +1,12 @@
+#include "complex_impl.h"
+
+/* acosh(z) = i acos(z) */
+
+double complex cacosh(double complex z)
+{
+	int zineg = signbit(cimag(z));
+
+	z = cacos(z);
+	if (zineg) return CMPLX(cimag(z), -creal(z));
+	else       return CMPLX(-cimag(z), creal(z));
+}