Square root of the entries of x using the CORDIC algorithm

This is a vectorized implementation in native Matlab code of the CORDIC algorithm for the square root.

This function computes the square root of each entry of the real-valued vector x,

using the CORDIC algorithm. It performs a number of iterations equal to n

(at each iteration, the binary accuracy rougly increases by one).

This is a vectorized implementation, in native Matlab code,

able to compute the square roots for all the entries of the

vector x.

Differently from Matlab sqrt, it returns NaN for negative entries

instead of the positive complex square root.

Please also notice that Matlab cordicsqrt will return zeros for

negative entries of x.

Possible improvement: use bit shift operations to generate the required powers of two.