单变量 H(x)=theta*x; 惩罚函数 J=sum(H(x)-y).^2/(2*m) 阶梯下降计算变量参数 T=theta(theta1,theta2); 如何计算 theta1和theta2 一步到位计算 theta1=theta1-apha((X*theta-y).*X(:1)) theta2=theta2-apha((X*theta-y).*X(:2)) 吴恩达作业1 Comput Cost for i=1:m J=J+(X(i,:)*theta-y(i)).^2/(2*m); end Gradiet descent theta(1)=theta(1)-alpha*(1/m)*(sum((X*theta-y).*X(:,1)));; theta(2)=theta(2)-alpha*(1/m)*(sum((X*theta-y).*X(:,2)));;