Use 0.0 for zero of type double

src/samplefunctional.hh

@@ -47,7 +47,7 @@ class SampleFunctional {
     // TODO: collinearity checks suck
     if (pg * x == pg.two_norm() * x.two_norm() &&
         -(mg * x) == mg.two_norm() * x.two_norm()) {
-      ret = SmallVector(0);
+      ret = SmallVector(0.0);
       return;
     } else if (pg * x >= 0 && mg * x >= 0) {
       ret = pg;