You should also read Kahan's commentary on the book: https://people.eecs.berkeley.edu/~wkahan/EndErErs.pdf https://people.eecs.berkeley.edu/~wkahan/EndErErs.pdf

You should also read Kahan's commentary on the book: https://people.eecs.berkeley.edu/~wkahan/EndErErs.pdf https://people.eecs.berkeley.edu/~wkahan/EndErErs.pdf. Also, note that since the publication of the End of Error, Gustafson has given up on the original variable-length unums described in the book and switched to "posits" (or "type III unums").