1 files changed, 13 insertions, 0 deletions
diff --git a/src/cmd/map/libmap/ccubrt.c b/src/cmd/map/libmap/ccubrt.c
new file mode 100644
index 00000000..8a7af566
--- /dev/null
+++ b/src/cmd/map/libmap/ccubrt.c
@@ -0,0 +1,13 @@
+#include <u.h>
+#include <libc.h>
+#include "map.h"
+
+void
+ccubrt(double zr, double zi, double *wr, double *wi)
+{
+	double r, theta;
+	theta = atan2(zi,zr);
+	r = cubrt(hypot(zr,zi));
+	*wr = r*cos(theta/3);
+	*wi = r*sin(theta/3);
+}