comments

polynomial.cpp

@@ -79,6 +79,9 @@ namespace util { namespace polynomial {
         const float _c = coeffs[2];
         const float _d = coeffs[3];
 
+        // Take care of degenerate quadratic cases. We can also pass off if 'd'
+        // is zero, but the benefit isn't clear given we have to merge results
+        // at the end anyway.
         if (almost_zero (_a)) {
             auto s = solve<2> ({_b, _c, _d});
             return {s[0], s[1], std::numeric_limits<float>::quiet_NaN () };

polynomial.hpp

@@ -25,6 +25,9 @@
 
 namespace util {
     namespace polynomial {
+        // Invalid solutions are represented by NaN. They are guaranteed to
+        // be at the end of the solution list, so they are safe to skip on the
+        // first instance.
         template <size_t S>
         std::array<float,S>
         solve (std::array<float,S+1>);