1 files changed, 17 insertions, 0 deletions
diff --git a/libc-top-half/musl/src/complex/casin.c b/libc-top-half/musl/src/complex/casin.c
new file mode 100644
index 0000000..3244beb
--- /dev/null
+++ b/libc-top-half/musl/src/complex/casin.c
@@ -0,0 +1,17 @@
+#include "complex_impl.h"
+
+// FIXME
+
+/* asin(z) = -i log(i z + sqrt(1 - z*z)) */
+
+double complex casin(double complex z)
+{
+	double complex w;
+	double x, y;
+
+	x = creal(z);
+	y = cimag(z);
+	w = CMPLX(1.0 - (x - y)*(x + y), -2.0*x*y);
+	double complex r = clog(CMPLX(-y, x) + csqrt(w));
+	return CMPLX(cimag(r), -creal(r));
+}