Addresses comments.

Signed-off-by: Franco Cipollone <franco.c@ekumenlabs.com>

include/maliput_sparse/geometry/line_string.h

@@ -78,13 +78,13 @@ class LineString final {
   /// A segment of a LineString.
   /// A segment is defined by a:
   /// - start index: index of the first coordinate of the segment.
-  /// - end index: index of the last coordinate of the segment, in general it is the start index + 1.
+  /// - end index: index of the last coordinate of the segment, it is expected to be `start index + 1` as `LineString`'s
+  /// constructor
+  ///              builds the segments from consecutive coordinates.
   struct Segment {
-    /// Defines an interval in the P value of the parametrized LineString.
+    /// Defines an interval in the @f$ p @f$ value of the parametrized LineString.
     /// The Less than operator is defined to allow the use of this struct as a key in a collection like std::map.
     struct Interval {
-      // Interval() = default;
-
       /// Creates a Interval.
       /// @param min_in Is the minimum value of the interval.
       /// @param max_in Is the maximum value of the interval.
@@ -96,7 +96,7 @@ class LineString final {
       /// @param min_max Is the minimum and maximum value of the interval.
       Interval(double min_max) : min(min_max), max(min_max) {}
 
-      // Less than operator.
+      /// Less than operator.
       bool operator<(const Interval& rhs) const {
         if (min < rhs.min) {
           return max <= rhs.max ? true : false;

src/geometry/utility/geometry.cc

@@ -290,10 +290,7 @@ CoordinateT InterpolatedPointAtP(const LineString<CoordinateT>& line_string, dou
   const CoordinateT& end = line_string[bound_points.idx_end];
   const CoordinateT d_segment{end - start};
   const double remaining_distance = p - bound_points.length;
-  if (remaining_distance < kEpsilon) {
-    return start;
-  }
-  return start + d_segment.normalized() * remaining_distance;
+  return remaining_distance < kEpsilon ? start : start + d_segment.normalized() * remaining_distance;
 }
 
 double GetSlopeAtP(const LineString3d& line_string, double p, double tolerance) {
@@ -309,7 +306,7 @@ double GetSlopeAtP(const LineString3d& line_string, double p, double tolerance)
 template <typename CoordinateT>
 BoundPointsResult GetBoundPointsAtP(const LineString<CoordinateT>& line_string, double p, double tolerance) {
   p = maliput::common::RangeValidator::GetAbsoluteEpsilonValidator(0., line_string.length(), tolerance, kEpsilon)(p);
-  const auto segment = line_string.segments().at(typename LineString<CoordinateT>::Segment::Interval{p});
+  const auto segment = line_string.segments().at({p});
   return {segment.idx_start, segment.idx_end, segment.p_interval.min};
 }