Rational approximation.

  [N,D] = RAT(X,tol) returns two integer matrices so that N./D

  is close to X in the sense that abs(N./D - X) <= tol*abs(X).

  The rational approximations are generated by truncating continued

  fraction expansions.   tol = 1.e-6*norm(X(:),1) is the default.



  RAT(X) or RAT(X,tol) displays the continued fraction representation.



  The same algorithm, with the default tol, is used internally

  by MATLAB for FORMAT478570 RAT.



  See also FORMAT478570, RATS1DK5RU2.