matlab - Error: Output argument "Clus_Area" (and maybe others) not assigned during call to -


have 2 matrices, dimensions 1440 rows 241 columns. first matrix populates each cell area, , second contains values 0 871. these cells grouped, , values 1 871 represent different groups, ie group 1 comprised of 10 neighboring cells, group 2 comprised of 20 neighboring cells, etc.

i want build third matrix, 871 rows 1 column, lists area of each group of cells second matrix, areas calculated summing relevant cells first matrix.

i tried running function, keep getting error: 

clear  clear load clusters_28aug.mat;   ar = a>0;  u = cluster_area(ar)

error in cluster_area (line 13) = 1; output argument "clus_area" (and maybe others) not assigned during call to.

i thought variable assigned within function. how can fix this?

here code: 

function clus_area = cluster_area(ar) % summer 2013 project % % purpose:  determine area of each cluster, adding individual areas of each cell within cluster. %  input %  ar(i,j) = clusters id'd, on 1440 x 241 matrix % % output % clus_area(i,j) = area of each cluster, single column vector, indexed cluster #  = 1; j = 1;  = 1:1440;  %for longitudes             j = 1:120;  %for 30s equator, convert 0.25 deg lon km, varies latitude                  if ar > 0;                           b_1 = (111.41288*cosd(abs((0.25*(j+239))-90)))-(0.0935*cosd(abs(3*((0.25*(j+239))-90))))+(0.00012*cosd(abs(5*((0.25*(j+239))-90))));             b_2 = (111.41288*cosd(abs((0.25*(j+240))-90)))-(0.0935*cosd(abs(3*((0.25*(j+240))-90))))+(0.00012*cosd(abs(5*((0.25*(j+240))-90))));              %use area formula trapezoid = 1/2 h (b_1+b_2), h = 27.8km             area_cell = (((0.5)*27.8*1000)*((b_1+b_2)*1000));  %ans converted m^2              %add cell areas cluster area             clus_area(i,j) = sum(area_cell);             disp('clus_area')             %populate grid_lat_lon area of each cell             %grid_lat_lon(i,j) = area_cell;                  end           end           j = 121:241;  %for equator 30n, convert 0.25 deg lon km, varies latitude         if ar > 0;                       b_1 = (111.41288*cosd(((0.25*(j+239))-90)))-(0.0935*cosd((3*((0.25*(j+239))-90))))+(0.00012*cosd((5*((0.25*(j+239))-90))));             b_2 = (111.41288*cosd(((0.25*(j+240))-90)))-(0.0935*cosd((3*((0.25*(j+240))-90))))+(0.00012*cosd((5*((0.25*(j+240))-90))));              %use area formula trapezoid = 1/2 h (b_1+b_2), h = 27.8km             area_cell = (((0.5)*27.8*1000)*((b_1+b_2)*1000));  %ans converted m^2                         %add cell areas cluster area             clus_area(i,j) = sum(area_cell);             disp('clus_area')             %populate grid_lat_lon area of each cell             %grid_lat_lon(i,j) = area_cell;                  end                            end      end z = clus_area(i,j); end

don't mean say

if ar(i,j)>0

i'm not sure semantics of if statement when expression results in array, think might require elements of expression true.


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