MATLAB: Conversion function taking a very long time to run in loop, anyway to improve

for loop

I created a function that does a simple conversion to my data with two coordinates being the input (below)
%%

function [ GazeDirDegrees ] = ConvertGazeDir( GazeDir1,GazeDir2 )
GazeDirDegrees = 180*asin(GazeDir1/sqrt(GazeDir1.^2+GazeDir2.^2))/pi
end
I am running this in a loop over 120 cells, with each cell containing 1000-1700 data points. As you can imagine this means that the function has to be called over 120,000 times. Not only that, but I have to run this loop 4 times for 4 different variables. (below is an example for just one variable))
%%
for i = 1:length(LeftGazeDirX)
    for b = 1:length(FilteredLeftGazeDirX{1,i})
     ConvLeftGazeDirX{b,i} = ConvertGazeDir(FilteredLeftGazeDirX{1,i}(b,1),FilteredLeftGazeDirZ{1,i}(b,1))
    end
end
Not sure if there is anything I can do to make this run more efficiently, as it currently takes about 20 seconds for a single cells worth of data.

Best Answer

Vectorize your formula by replacing the / with ./ and then you can pass in entire cells (provided the two cells are the same size)
Also you can improve performance slightly by making it 180/pi * .... instead of 180*.../pi so that the division by pi only has to be done once
Also consider using asind without the 180/pi
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