If one of the methods (Krawczyk / Newton) cannot say if there is or is not a root, then for only that interval the precision (and the tolerance) can be doubled and try again. This doubling of the precision can be continued as long as is necessary to say something more precise about the root, until some predefined maximum limiting precision is reached.
If one of the methods (Krawczyk / Newton) cannot say if there is or is not a root, then for only that interval the precision (and the tolerance) can be doubled and try again. This doubling of the precision can be continued as long as is necessary to say something more precise about the root, until some predefined maximum limiting precision is reached.