| From: Thomas Bushnell BSG <xxxxxx@becket.net>
 | Date: Thu, 02 Jun 2005 08:23:36 -0700
 |
 | Aubrey Jaffer <xxxxxx@alum.mit.edu> writes:
 |
 | > So in a Scheme implementation which has "arbitrarily big" precision,
 | > how many digits is (sqrt 2)?  How many digits is (sin 7/5)?
 |
 | There is no function "precision-of", so there is no need for an
 | answer.  Arbitrarily big precision arithmetic (generally) works pretty
 | well; you carry around symbolic representations and operate on them.

To first order:

  (define (precision-of x) (string-length (number->string x)))

R5RS requires all numbers to have external representations; and it
specifies the allowed formats.