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2012-03-29 12:25:40
1Added documentation of MIT Scheme's floating-point support, including support for !NaNs and positive and negative infinities, since it's not yet documented in the MIT Scheme manual.history

MIT Scheme now has support for positive and negative infinities and for signaling (the default) and non-signaling NaNs.

The printed representations are #[+inf], #[-inf], and #[NaN], and are not readable.

To disable signaling: (flo:ignoring-exception-traps thunk). For example:

(flo:ignoring-exception-traps (lambda () (let* ((i (* 1.0e200 1.0e200)) (n (- i i))) (list i (- i) n)))) ;Value 13: (#[+inf] #[-inf] #[NaN])

These procedures are available for manipulating the floating-point environment:

flo:nan? flo:raise-exceptions! flo:restore-exception-flags! flo:rounding-mode flo:rounding-modes flo:save-exception-flags flo:set-environment! flo:set-rounding-mode! flo:set-trapped-exceptions! flo:significand-digits-base-2 flo:significand-digits-base-10 flo:supported-exceptions flo:test-exception-flags flo:test-exceptions flo:trap-exceptions! flo:trappable-exceptions flo:trapped-exceptions flo:untrap-exceptions! flo:update-environment! flo:with-default-environment flo:with-exceptions-trapped flo:with-exceptions-untrapped flo:with-rounding-mode flo:with-trapped-exceptions