The simple continued fraction is both the most interesting and important kind of continued fraction.
For the convergence of the continued fraction of the second class there is no complete criterion.
The continued fraction is therefore incommensurable, and cannot be unity.
There is, however, a different way in which a Series may be represented by a continued fraction.
Similarly the continued fraction given by Euler as equivalent to (e - 1) (e being the base of Napierian logarithms), viz.
He had not then the continued fraction, a mode of representation which he gave the next year in his work on the square root.
If a or b is unity, a/b cannot be converted into a continued fraction with unit numerators, and the above method fails.