Re: Best processors for trig?

On Fri, 30 Mar 2007 20:06:57 GMT, Tauno Voipio
<tauno.voipio@xxxxxxxxxxxxx> wrote:

larwe wrote:
On Mar 30, 1:46 pm, 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.


You can also look at CORDIC functions. These can be implimented in
an FPGA. Apparently the first HP calculators used this method to
calculate all the normal trig functions to high precision using CORDIC
functions.

Regards
Anton Erasmus

.

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