[WP-34S] DEG and RAD - diffs

[Claudio L.]

(06-05-2014 07:57 PM)pito Wrote:  It means the "less precise" result of the test in DEG mode is caused by the internal conversions rad<->deg as you have described above.
My question is whether the internal conversions (basically multiplication by a constant) done in 39digits may cause such difference in the 34digits test result.

Not just the pi/180 constant multiplication:

sin(9deg) = "some value" / This first value is the same when you work with radians.

cos(sin(9deg)) --> Since the calc is in degrees, you are actually (internally) doing cos(sin(9deg)*pi/180), which is a completely different value when you run it in radians or degrees, since in one case you are interpreting sin(9deg) as an angle in degrees, and in the other case you are interpreting as an angle in radians.
Now when working in degrees, you are taking the value of the sin() and making it much smaller (pi/180 smaller). Smaller angles are harder test cases and have more errors on trig function algorithms.

So it's very likely the result will have many more changed digits when you run it in DEG mode, and the error doens't come only from the additional conversions, but from the fact that you are using much smaller angles.

Claudio