[algorithm] Added getter for data source in interpolators

include/rtac_base/interpolation.h

@@ -35,6 +35,9 @@ class Interpolator
 
     public:
 
+    const Vector& x0() const;
+    const Vector& y0() const;
+    
     Vector operator()(const Vector& x) const;
     unsigned int size() const;
     
@@ -122,6 +125,18 @@ Interpolator<T>::Interpolator(const Vector& x0, const Vector& y0) :
     assert(x0_.size() == y0_.size());
 }
 
+template <typename T>
+const typename Interpolator<T>::Vector& Interpolator<T>::x0() const
+{
+    return x0_;
+}
+
+template <typename T>
+const typename Interpolator<T>::Vector& Interpolator<T>::y0() const
+{
+    return y0_;
+}
+
 /**
  * Interpolate at values x.
  *