I've been clawing at my mind for a while regarding this, I pray somebody can help me. I was implementing a method from a computer science paper when I came accross this: [PLAIN]http://www.mattkent.eu/challenge.png [Broken] Bearing in mind that x is a vector, epsilon is a vector of integers (and x raised to this is performed component wise), I can't tell what exactly the Sigma is summing. Firstly what does a sigma of index i mean in the matrix A? What exactly would be summed there? Is it the 'sum of the vector components for a given i' or the 'sum of all vectors where each has been raised to epsilon'? And secondly, in the definition of the b vector, what is the sigma doing here? There's absolutely no index or limit associated with it. The t value is essentially a constant. So is this saying 'sum up the vectors components (once multiplied with t)' ? I'm at a loss. Please help super mathematicians.