diff --git a/aos/commonmath.h b/aos/commonmath.h
new file mode 100644
index 0000000..0130992
--- /dev/null
+++ b/aos/commonmath.h
@@ -0,0 +1,43 @@
+#ifndef AOS_MATH_H_
+#define AOS_MATH_H_
+
+#include <cmath>
+
+namespace aos {
+
+// Clips a value so that it is in [min, max]
+static inline double Clip(double value, double min, double max) {
+  if (value > max) {
+    value = max;
+  } else if (value < min) {
+    value = min;
+  }
+  return value;
+}
+
+template <typename T>
+static inline int sign(T val) {
+  if (val > T(0)) {
+    return 1;
+  } else {
+    return -1;
+  }
+}
+
+// Adds deadband to provided value.  deadband is the region close to the origin
+// to add the deadband to, and max is the maximum input value used to re-scale
+// the output after adding the deadband.
+static inline double Deadband(double value, const double deadband,
+                              const double max) {
+  if (::std::abs(value) < deadband) {
+    value = 0.0;
+  } else if (value > 0.0) {
+    value = (value - deadband) / (max - deadband);
+  } else {
+    value = (value + deadband) / (max - deadband);
+  }
+  return value;
+}
+}  // namespace aos
+
+#endif  // AOS_MATH_H_