matrix row-wise polynomial fit

This function performs row-wise polynomial regression fitting of a 2D matrix. Each row is a polynomial regression problem. The function utilizes matrix operations instead of looping through each matrix row, so can work on a matrix with large number of rows. Other matrices of different dimensions, as long as the regression problem is along only one dimension, can be reshaped into a 2D matrix, where regression problems are placed along the 2nd dimension, and use this function to solve the problem.