You define a function with one output argument result:
function result = singularitytest(A)
Inside the function you define several variables, but you do not define result anywhere. Thus the error: if you do not tell MATLAB what result is, how do you expect it to return anything?
Perhaps you meant to do this:
function result = singularitytest(A)
d = det(A);
result = cond(d) <= 1e-10;
end
