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吴恩达机器学习 Part2

Model representation
univariate linear regression

univariate linear regression

Cost function
有时候也会被叫做平方误差代价函数

Gradient descent algorithm 梯度下降法
Gradient descent algorithm

Gradient descent algorithm


learning rate后面的部分是derivative
假如阿尔法太小,梯度就会减缓。假如阿尔法太大,梯度下降可能超过最小值。

吴恩达机器学习 Part1

Machine learning definition
Well-posed learning problem: A computer program is said to learn from experience E with respect to some task T and some performance measure P, if its performance on T, as measured by P, improves with experience E.

Machine learning algorithms:

  • supervised learning 我们教计算机做某件事
  • unsupervised learning 计算机自己总结学会做某事

Others: Reinforcement learning, recommender systems.


supervised learning
想法是在监督学习中,对于数据集中的每个样本,我们想要算法预测并得到正确答案。
分类问题 classification problem 回归问题 regression problem

unsupervised learning
把大量的数据给到computer 计算机自习学会做某事