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acos_fx16(x) with x>0.9?

Question asked by Oli on Nov 7, 2011
Latest reply on Nov 18, 2011 by Oli

Dear Community,


According to the C/C++ Compiler  and Library Manual for Blackfin® Processors, the acos_fr16, acos_fr32, acos_fx16 and acos_fx32 functions are defined for fractional input  values between 0 and 0.9. I have verified experimentally that this is indeed the case.

My question is therefore: how can I compute acos(x) for x=[0.9;1] without resorting to floating-point functions (or a LUT)?

As far as I know, there is no simple trigonometric identity or symmetry property that allows one to compute this from the available interval.


Thank you for the help!