| Date: Mon, 20 Feb 2012 01:07:09 -0800 | From: Per Bothner <[email protected]> | | IEEE allows multiple NaN values. They're unlikely to matter for | Scheme implementations or code, but I think a note is in order. | | I suggest something like the following: | | IEEE 754 specifies multiple NaN values. A Scheme implementation | may collapse all NaN values to a single "representative NaN", or | there may be multiple NaN values. In the latter case, the +nan.0 | is the "canonical NaN" value. Scheme functions in general must | treat all NaN values as equivalent. This specifically includes the | nan? functions, which must be true for all NaN values. The only | standard Scheme function which can distingish different NaN values | is eqv?, though it is also permitted to treat all NaN values as | eqv?
EQ? is allowed to distinguish different NaN values. It is better to let EQ? make this distinction than EQV?. _______________________________________________ Scheme-reports mailing list [email protected] http://lists.scheme-reports.org/cgi-bin/mailman/listinfo/scheme-reports
