HP-35: Sin and cos function formulas, another point of view

[Albert Chan]

When I did the rough error test with Mathematica, the float is done in IEEE double.
Thus, multiply by 2 and divide by 2 is exact.

Not the case with decimal digits setup. (e.g. calculator with BCD digits)

Say, a calculator had 12 decimal digits internal precision,

x = 567812345678
2x = 1135624691356, internally round-up to 1135624691360

My guess is calculator will be less accurate with half-angle formula.