How are the terms separated? If separated using '+' operator, then try the following code
str = '10*z^2*w^4 + 5*w^2*l^2 + 2*z^6';
patterns = {'w\^([0-9]*)', 'l\^([0-9]*)', 'z\^([0-9]*)'};
tokens = cellfun(@(p) {regexp(strsplit(str, '+'), p, 'tokens')}, patterns);
y = cellfun(@(token) {cellfun(@helperFun, token)}, tokens);
y = reshape(cell2mat(y(:)), 1, []);
function y = helperFun(x)
if ~isempty(x)
y = str2double(x{1}{1});
else
y = 0;
end
end
Result
>> y
y =
4 0 2 2 2 0 0 0 6
