replace std::copy with std::copy_n where appropriate

more expressive

opm/elasticity/mortar_utils.hpp

@@ -27,7 +27,7 @@ class MortarUtils {
     static void extractBlock(Vector& x, const Vector& y, int len, int start = 0)
     {
       x.resize(len);
-      std::copy(y.begin() + start, y.begin() + len + start, x.begin());
+      std::copy_n(y.begin() + start, len, x.begin());
     }
 
     //! \brief Inject a range of indices into a vector
@@ -37,7 +37,7 @@ class MortarUtils {
     //! \param[in] start The first index in the range
     static void injectBlock(Vector& x, const Vector& y, int len, int start = 0)
     {
-      std::copy(y.begin(), y.begin() + len, x.begin() + start);
+      std::copy_n(y.begin(), len, x.begin() + start);
     }
 };
 

opm/upscaling/CornerpointChopper.hpp

@@ -155,7 +155,7 @@ namespace Opm
                     int pos = (dims_[0] + 1)*j + i;
                     int new_pos = (new_dims_[0] + 1)*(j-jmin) + (i-imin);
                     // Copy all 6 coordinates for a pillar.
-                    std::copy(COORD.begin() + 6*pos, COORD.begin() + 6*(pos + 1), new_COORD_.begin() + 6*new_pos);
+                    std::copy_n(COORD.begin() + 6*pos, 6, new_COORD_.begin() + 6*new_pos);
                     if (resettoorigin) {
                         // Substract lowest x value from all X-coords, similarly for y, and truncate in z-direction
                       new_COORD_[6*new_pos]     -= x_correction;