Re: Best processors for trig?

CBFalconer wrote:

Tauno Voipio wrote:
larwe wrote:
Tim Wescott <t...@xxxxxxxxxxxxxxxx> wrote:

A floating point DSP, as noted.

What's the canonical method of doing this? Taylor series
approximations?

Of course, the arguments have to be reduced first to
the range of the period (2 * pi for sin and cos, pi
for tan). The reduced range is often split into some
sub-ranges with different coefficients.

The least-maximum error polynomial for approximation
is obtained by developing the function to a series
of Chebysev polynomials. This method gives less error
than a corresponding Taylor or MacLaurin series.

The trig functions and exponential are quite polynomial-
friendly. The most difficult of the elementary functions
is the logarithm, its Taylor series uses half of an
infinity to converge.

A fine book on the subject is Hastings "Approximations for Digital
Computers". Someone stole mine about 20 years ago.

It's a pain when that happens. I managed to get a copy a few years ago from
Amazon. They do have links to old book stockists so you can sometimes find
an old classic like that through them.

Also worth looking up are DDA algorithms which are often quite fast.

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