## powMrec

Power of M matrix by recurrence.

Power of M matrix by recurrence.

F = powMrec(x, order)

F = powMrec(x, order) is a faster and stable way to compute M^order, order = 2, 3, ... Was avoided the direct products of these matrices, and instead that we applied a reccurrence formulation: m_{i, j}^(order) = m_{i-1, j}^(order-1)*alpha_{i-1} + m_{i, j}^(order-1)*beta_{i} + m_{i+1, j}^(order-1)*gamma_{i+1}, where alpha, beta and gamma are the coefficients of orthogonal polynomials three term recurrence relation, shifted to [a, b].

x = independent tau variable (itau object). order = power order (integer).

F = x^order = M^order (double matrix).