Ng机器学习编程作业matlab实现LR时里有这样一段
%% ============= Part 3: Optimizing using fminunc =============
% In this exercise, you will use a built-in function (fminunc) to find the
% optimal parameters theta.
% Set options for fminunc
options = optimset('GradObj', 'on', 'MaxIter', 400);
% Run fminunc to obtain the optimal theta
% This function will return theta and the cost
[theta, cost] = ...
fminunc(@(t)(costFunction(t, X, y)), initial_theta, options);
...
不是很能理解optimset和fminunc的用法
[theta, cost] = ...
fminunc(@(t)(costFunction(t, X, y)), initial_theta, options);
我是matlab初学者，这里需要用这个函数来实现梯度下降算法，也就是迭代多次学习theta。请问在fminunc里是怎样实现迭代的呢？那个@t是什么意思？optimset里的‘GradObj’是什么意思？
跪等大神解救！
