New Post: How to apply operation over vector from each row/column of a matrix?

 public static Matrix<T> AddVectorOnEachColumn<T>(this Matrix<T> m1, Vector<T> v, T scale) where T : struct, 
                                                                                                     IEquatable<T>, IFormattable
 {
     Contract.Requires(m1 != null);
     Contract.Requires(v != null);
 
     if (m1 is Matrix<float>)
     {
         var fm1 = m1 as Matrix<float>;
         var fv = v as Vector<float>;
         var fscale = (float)(object)scale;
 
         return fm1.MapIndexed((i, j, value) => fm1.At(i, j) + fscale * fv.At(j)) as Matrix<T>;
     }
     else if (m1 is Matrix<double>)
     {
         var dm1 = m1 as Matrix<double>;
         var dv = v as Vector<double>;
         var dscale = (double)(object)scale;
 
         return dm1.MapIndexed((i, j, value) => dm1.At(i, j) + dscale * dv.At(j)) as Matrix<T>;
     }
     else throw new NotSupportedException("Type: {0} is not supported by the Matrix<T> class.");
 }