math: Add a function for calculating the arcsin #2
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The function is based on a binary search.
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Why not implement this function in InfiniTime? |
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The only reason I don't want to implement it in InfiniTime is because I'd have to duplicate the 91-element lookup table. It saves 182 bytes by not duplicating it. |
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I think you can implement it by accessing the array through the _lv_trigo_sin() function. |
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That is possible, but I'd be concerned about the overhead added by the the branches and modulo. I can try it anyway though. |
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It seems that it works well enough implementing this in InfiniTime. See InfiniTimeOrg/InfiniTime#826. |
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The function is based on a binary search. It performs a binary search, and then does a naive interpolation, because the inputs aren't necessarily in the lookup table.
It has a slight "issue" where if
argis-32768it accesses a value out of bounds, which could be mitigated by adding an if statement to the beginning of the function that just returns -90 if arg is -32768. I don't think that's necessary, because the user of the function should just make sure that the inputs are within the range [-32767, 32767].It's necessary for a better algorithm I'm working on for raise to wake.