return the value by linear interpolation.

opm/polymer/PolymerProperties.cpp

@@ -65,10 +65,10 @@ namespace Opm
         return water_vel_vals_;
     } 
 
-    const std::vector<double>&
-    PolymerProperties::shearVrf() const
+    double
+    PolymerProperties::shearVrf(const double velocity) const
     {
-        return shear_vrf_vals_;
+        return Opm::linearInterpolation(water_vel_vals_, shear_vrf_vals_, velocity);
     }
 
     double PolymerProperties::viscMult(double c) const

opm/polymer/PolymerProperties.hpp

@@ -166,7 +166,7 @@ namespace Opm
         
         const std::vector<double>& shearWaterVelocity() const;
 
-        const std::vector<double>& shearVrf() const;
+        double shearVrf(const double velocity) const;
 
         double viscMult(double c) const;