[WP-34S] DEG and RAD - diffs

[Thomas Klemm]

(06-07-2014 01:46 AM)Claudio L. Wrote:  You're right, that term won't lose precision.

As Pauli already pointed out there's no cancellation since:

\[\frac{1}{\sqrt{1+x^2}}=1-\frac{x^2}{2}+\ldots\]

For a small x this will be close to 1 and thus \(\sin(x)\approx\tan(x)\).

Quote:I looked at my code, and here's where I was losing digits:

// COMPUTE ACOS(X) = ATAN2(SQRT(1-X^2),X)

when x~1 (ACOS(X)~0) I couldn't get all the digits right

You might have a look at how the HP-48 calculates the complex arccos.

Cheers
Thomas