1 files changed, 11 insertions, 0 deletions
diff --git a/src/math/copysign.c b/src/math/copysign.c
new file mode 100644
index 00000000..038b8b4c
--- /dev/null
+++ b/src/math/copysign.c
@@ -0,0 +1,11 @@
+#include "libm.h"
+
+double copysign(double x, double y) {
+	union dshape ux, uy;
+
+	ux.value = x;
+	uy.value = y;
+	ux.bits &= (uint64_t)-1>>1;
+	ux.bits |= uy.bits & (uint64_t)1<<63;
+	return ux.value;
+}