prin1 and ~E produce different outputs.

[anonymous]

(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.

[rtoy]

One particular example is

(format nil "~E" 1.234567890123456789d4)
"1.2345678901234565d+0"

The right answer is

"1.2345678901234567d+0"

which is what prin1 returns.

This should now be fixed in CVS.