After some consultation with my class this quarter,
it seems clear that the previous defaults and nearby
variations are completely hopeless for colorblind people
(there are at least 3 in this class). So go with the
defaults used in the HtDP languages, which have been
vetted by saidsame 3 people.
binding site (with a green/yellow bubble) when the mouse moves over
any one of them
This change comes about because of the recent fixes to the
interactivity wrt to the rename menu. Basically, in order to fix the
bug (but still preserve the interactivity optimization), check syntax
changed from sending the information "here is a place to offer a
rename for these identifiers" to "here is a set of identifiers that
are all free-identifier=?" (the difference being that the latter does
not imply you got them all (which enables the optimization) and that
the information is slightly less rename-menu specific (which enables
the change in this commit))
An extflonum is like a flonum, but with 80-bit precision and
not a number in the sense of `number?': only operations such as
`extfl+' work on extflonums, and only on platforms where extflonums
can be implemented by hardware without interefering with flonums
(i.e., on platforms where SSE instructions are used for
double-precision floats).
[Patch provided by Michael Filonenko and revised by Matthew.]
The compiler tracks information about bindings that are known to
hold extflonums, but the JIT does not yet exploit this information
to unbox them (except as intermediate results).
Note: With this refactoring, `math/utils' no longer depends on `rackunit'.
* (flexp2 x) computes (flexpt 2.0 x) but in about 1/3 the time for integer
`x' using a lookup table. Written for exact argument reduction in `fllog2'
after discovering that (flexpt 2.0 x) was the main performance bottleneck.
* (fllog2 x) computes (/ (fllog x) (fllog 2.0)) with near perfect accuracy.
Invented an algorithm to compute it with at least 8 extra bits before
final rounding; quite pleased with the result. Needed `fllog2' to ensure
(fllogb 2.0 x) would be exact when `x' is a power of two.
* (fllogb b x) computes (/ (fllog x) (fllog b)) with better accuracy, and
also handles limit values in a way that's consistent with the mathematical
limits. When those are ambiguous, it's consistent with `flexpt', which
follows IEEE 754 and C99. Otherwise returns +nan.0. See docs for details.
* `bflogb' is currently just for testing `fllogb'.
* Refactored FPU testing and documented it. So far, the only documented way
to do it is by calling `test-floating-point', which runs a comprehensive
deterministic+randomized suite of tests and returns a list representing
failed tests. I'll document individual tests after I document flonum
expansions and result/error functions like `fl+/error'.
* Added `fllog2' and `fllogb' to the flonum tests.
