ARM sinus lookup tables 5x faster than math.h - TM4C123GXL Cortex M4F

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Lately, I was working with IIR filter so in CMSIS repo I saw look-up table with sinus value. I was wondering how much faster it works then math.h sinus function.

The name of the function which uses a lookup table is arm_sin_f32() which is part of arm_math.h

Lets first compare results calculated with the lookup table and math.h sin function. Result2 are from the lookup table (arm_sin_f32() -> arm_math.h) and result1 are from sinus function (sin() -> math.h).




From results is seen that after decimal point 4-5 digits are similar so take care with that. 

I have done an iteration of 100 000 calculation and I was measuring the time needed for math.h sin and got 9726 [ms], and for arm_math.h 2006 [ms] which is almost 5x time faster. 




In the photo below I added sinus wave for both calculations. Blue is result1 and red is result2. You can see they overlap. 



You can check the code on the link. 

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