How to create a loop which nan means every datapoint of three components

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Rebecca Ellis 2018-9-6

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编辑： ADragon 2018-9-7

I have 3 datasets at 11564597 data points each - my calculation is U = nanmean(sqrt((u).^2+(v).^2+(w).^2)); to get the mean flow of the 3 sinusoidal curves. To get an array that has 11564597 points to plot on top of the 3 components as the mean flow of the three compontents.

My code so far is:

U= NaN*ones(length(velocity_x_nortek.smooth));
for i = 1:length(velocity_x_nortek.smooth)
    U(i)= nanmean(sqrt((velocity_x_nortek.smooth).^2+(velocity_y_nortek.smooth).^2+(velocity_z_nortek.smooth).^2);
end

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ADragon 2018-9-6

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Hi Rebecca, you do not need the for loop since the equation can operate on arrays. Just use:

U = nanmean(sqrt((velocity_x_nortek.smooth).^2+(velocity_y_nortek.smooth).^2+(velocity_z_nortek.smooth).^2);
plot([velocity_x_nortek.smooth velocity_y_nortek.smooth velocity_z_nortek.smooth U])

Assuming you have column vectors for plotting.

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Rebecca Ellis 2018-9-7

在 MATLAB Online 中打开

The calculation is

   U = nanmean(sqrt((u).^2+(v).^2+(w).^2))
is correct - 
I just need to loop it that it does the calculation for every 11564597 points -

U = zeros(length(timevec), 1);

for i = 1:length(velocity_x_nortek.smooth)
    U(i)= nanmean(sqrt((velocity_x_nortek.smooth).^2+(velocity_y_nortek.smooth).^2+(velocity_z_nortek.smooth).^2));
end

The loop I have doesn't work ?

ADragon 2018-9-7

编辑：ADragon 2018-9-7

在 MATLAB Online 中打开

OK. You can add an index to your vector.

for i = 1:length(velocity_x_nortek.smooth)
    U(i)= nanmean(sqrt((velocity_x_nortek.smooth(i)).^2+(velocity_y_nortek.smooth(i)).^2+(velocity_z_nortek.smooth(i)).^2));
end

But you will be taking the mean of a scalar value. So I am confused as to what you are trying to do...

If you are trying to calculate RMS then switch mean and sqrt.

for i = 1:length(velocity_x_nortek.smooth)
      U(i)= sqrt(nanmean((velocity_x_nortek.smooth(i)).^2+(velocity_y_nortek.smooth(i)).^2+(velocity_z_nortek.smooth(i)).^2));
  end

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