Filter: notch filter: remove unneeded value and pre-multiply for speed #24250
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andyp1per
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Rebased and tested on the bench. Still getting good agreement with post filter estimate from filter tool, so all seems to be working as before. |
CraigElder
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CraigElder
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tridge
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I had spotted we could pre-multiply by a0 to same some runtime calculation and was looking at the betaflight filter code and they also have different handling of the "memory" elements that saves one value.
https://github.com/betaflight/betaflight/blob/90d09e2e5bccc9e21101811618be79621286f56e/src/main/common/filter.c#L210-L224
I have run this in my MATLAB thingy (#24249) result is the same to 10^-4. floating point math does mean the result comes out a tiny bit different. The difference is only due to the pre-multiplication of a0. The removal of
ntchsigmakes no difference to the result.