Warp <war### [at] tagpovrayorg> wrote:
>   I still see no rational reason to deliberately and on purpose break
> 99% of programs. What would be the point? Task switching takes a negligible
> amount of time, so skipping storing and loading the FPU registers would be
> a rather useless micro-optimization.

What would the purpose be of not including ISA, EISA, VESA or at least AGP slots
on mainboards anymore? Why does my new mainboard not have Sub-D connectors for
RS232 and parallel ports anymore? Why does it only provide a single RS232 port?
Why does it provide only a single IDE channel? Why does the BIOS only support a
single floppy disc drive? Will my old floppy streamer still work? Why doesn't
the mainboard provide at least a pin header for the classic game port and MIDI
interface? Why can't I run my old DOS games from XP's command window?

What's the intention behind this? Breaking existing hard- and software? Bloody
likely not. Phasing out old stuff that has come of age and starts to get in the
way? Bloody likely yes.

Declaring something as "deprecated" doesn't mean someone intends to remove it
coming spring. It just means that someone sees a potential benefit of phasing
it out over time - and wants to make sure that it will *not* break 99% of the
software when it's actually done.

So for software developers it is prudent to heed such deprecation statements.
Otherwise their software may end up being among the remaining 1% to be broken
some day in the future.

What's the bottom line in practice?

If your software doesn't live & breathe from fast trigonometrics, fingers off
the x87 FPU.

If your software can't do without a lot of trigonometrics and at the same time
needs to be fast, decide for yourself, but be aware that your software may not
live forever.

BTW, while trying to see what the compiler makes of sin() and cos(), I got the
impression that POV-Ray doesn't really need fast trigonometrics. It does need
to compute some now and then, but plain vector & matrix stuff is by far the
bulk of the floating-point math. As a matter of fact, some more frequent calls
to sin() and cos() have already been replaced by pre-computed tables quite some
time ago.

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