fix brackets

include/igl/copyleft/marching_cubes.cpp

@@ -379,8 +379,8 @@ public:
     // generate new vertex
     const Eigen::Matrix<typename DerivedPoints::Scalar, 1, 3> & p0 = points.row(i0);
     const Eigen::Matrix<typename DerivedPoints::Scalar, 1, 3> & p1 = points.row(i1);
-    typename DerivedValues::Scalar s0 = fabs(values[i0]-isovalue);
-    typename DerivedValues::Scalar s1 = fabs(values[i1]-isovalue);
+    typename DerivedValues::Scalar s0 = fabs(values(i0)-isovalue);
+    typename DerivedValues::Scalar s1 = fabs(values(i1)-isovalue);
     typename DerivedValues::Scalar t  = s0 / (s0+s1);
     num_vertices++;
     if (num_vertices > vertices.rows())