MATLAB: PointCloud object problems !!

Question

I will determine normals at each point of an array M (3 * 3) using "pcnormals" but here is the message that appears :

Expected ptCloud to be a pointCloud object

# [X1]= stlread('c1.stl');

X=unique(X1,'rows');

% pick up 3 random points

M= X(floor(rand(3,1)*(size(X,1)))+1,:);

normals = pcnormals(M,10);

Answer 1

M = pointCloud(M)