Calculate mean of matrix for specific interval

Hi all,

I have elevation data stored in a 121x721 matrix called DEM.

I want to calculate 2 things:

1) the cross-sectionally averaged mean elevation along the flume. i.e. the mean elevation per column of matrix DEM. (This works OK)

2) The cross-sectionally averaged mean elevation along the flume for DEM(11:110). So without the edges. (Does not work yet)

My code works for the first but not for the second thing I try to calculate.

See the minimal working example below to see the code I used.

What I need is a 1x721 array of the mean value of columns in DEM between 11 and 110.

Hope this makes sense and someone can point me in the right direction.

Thanks

%% MWE 
% DEM contains a digital elevation model (elevation data). 
DEM = rand(121,721);

% calcultate DEM means for full DEM  
DEM_mean = mean(DEM); % this returns a 1x721 array which is what I need 

% calculate DEM means for specific interval of DEM 
DEM_mean2 = mean(DEM,11:110); % this returns a 121x721 matrix, but I need a 1x721 array like above. 

Answer 1

[Konrad]

Hi Pelle,

you need to index your variable DEM correctly:

DEM_mean2 = mean(DEM(11:110,:));

Best, Konrad

[Pelle Adema]

Hi Konrad,

Thanks for your answer. This was indeed the problem and your solution gives me what I need.

Best,

Pelle