Hey guys, my stlwrite function is not working and i would like to know how to fix it. In the code C is random points

seeds=C;

Unrecognized function or variable 'C'.

[Ver,Cel,C_tst]=voronoi3d_cuboid(seeds,Vcub);
FK = zeros(100,3,312);
figure
hold on
axis('equal')
view([-36 27])
scatter3(seeds(:,1),seeds(:,2),seeds(:,3),25, ...
    'Marker','o','MarkerFaceColor',[1 0 0], 'MarkerEdgeColor','k');
scatter3(Ver(:,1),Ver(:,2),Ver(:,3),25, ...
    'Marker','o','MarkerFaceColor',[0 1 0], 'MarkerEdgeColor','r');

for k = 1:length(Cel)
    if ~isempty(Cel{k})
        col=rand(1,3);
        Vk = Ver(Cel{k},:); Fk = convhull(Vk);
        if exist('mergeCoplanarFaces.m','file')==2
            [Vk, Fk] = mergeCoplanarFaces(Vk, Fk);
            for i=1:length(Fk)
                patch('Vertices',Vk,'Faces',Fk{i},'FaceColor',col,'FaceAlpha',0.3)
            end
        else     
            trisurf(Fk,Vk(:,1),Vk(:,2),Vk(:,3),'FaceColor',col, ...
                'FaceAlpha', 1,'EdgeAlpha',1,'EdgeColor','k');
            %               
            
            FK(1:size(Fk,1),1:3,k) = Fk(:,1:3);
            VK(1:size(Vk,1),1:3,k) = Vk(:,1:3);
            
            
        end
    end
    
end


grid on
xlabel('X');ylabel('Y');zlabel('Z');
P = struct('faces',FK,'vertices',VK);
stlwrite('mytriangulation.stl',P);

[Rik]

Please post code that runs up to the error you indicate.