#1: prin1 and ~E produce different outputs. ------------------------+--------------------------------------------------- Reporter: anonymous | Owner: rtoy Type: defect | Status: assigned Priority: minor | Milestone: Component: Core | Version: Resolution: | Keywords: printing ------------------------+--------------------------------------------------- Changes (by rtoy):

* status: new => assigned * owner: somebody => rtoy

#1: prin1 and ~E produce different outputs. ------------------------+--------------------------------------------------- Reporter: anonymous | Owner: rtoy Type: defect | Status: assigned Priority: minor | Milestone: Component: Core | Version: 19c Resolution: | Keywords: printing ------------------------+--------------------------------------------------- Old description:

(let ((x (random 1d-3))) (values (prin1-to-string x) (format nil "~E" x)))

will produce different significant digits. I think the problem is in ~E which calls lisp::scale-exponent to scale the number between 0.1 and 1. I think we could just call flonum-to-digits which will give us the digits and the exponent. We can massage that into the desired digits and exponent as in scale-exponent, but we won't have the round-off problem.

Maybe.

New description:

{{{ (let ((x (random 1d-3))) (values (prin1-to-string x) (format nil "~E" x))) }}}

will produce different significant digits. I think the problem is in ~E which calls lisp::scale-exponent to scale the number between 0.1 and 1. I think we could just call flonum-to-digits which will give us the digits and the exponent. We can massage that into the desired digits and exponent as in scale-exponent, but we won't have the round-off problem.

Maybe.