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youtu.be/aircAruvnKk 잘 만듬 Cost Function Let's first define a few variables that we will need to use: L = total number of layers in the network s_lsl​ = number of units (not counting bias unit) in layer l K = number of output units/classes Recall that in neural networks, we may have many output nodes. We denote h_\Theta(x)_khΘ​(x)k​ as being a hypothesis that results in the k^{th}kth output. Our ..

Non-linear hypothesis Nerural Network There's this sense that if the same piece of physical brain tissue can process sight or sound or touch then maybe there is one learning algorithm that can process sight or sound or touch. And instead of needing to implement a thousand different programs or a thousand different algorithms to do, you know, the thousand wonderful things that the brain does, may..

ML:Logistic Regression Now we are switching from regression problems to classification problems. Don't be confused by the name "Logistic Regression"; it is named that way for historical reasons and is actually an approach to classification problems, not regression problems. To attempt classification, one method is to use linear regression and map all predictions greater than 0.5 as a 1 and all l..

Basic Operations Moving Data Around In the next video, I'd like to start talking about more sophisticated commands and how to use data around and start to process data in Octave. Moving Data Around Computing on Data Plotting Data Control Statements: for, while, if statement Vectorization

Multiple Features Note: [7:25 - \theta^TθT is a 1 by (n+1) matrix and not an (n+1) by 1 matrix] Linear regression with multiple variables is also known as "multivariate linear regression". We now introduce notation for equations where we can have any number of input variables. x(i)jx(i)mn=value of feature j in the ith training example=the input (features) of the ith training example=the number o..

Setting Up Your Programming Assignment Environment The Machine Learning course includes several programming assignments which you’ll need to finish to complete the course. The assignments require the Octave or MATLAB scientific computing languages. Octave is a free, open-source application available for many platforms. It has a text interface and an experimental graphical one. MATLAB is propriet..

ML:Linear Algebra Review Khan Academy has excellent Linear Algebra Tutorials (https://www.khanacademy.org/#linear-algebra) Matrices and Vectors Matrices are 2-dimensional arrays: ⎡⎣⎢⎢⎢adgjbehkcfil⎤⎦⎥⎥⎥ [a​b​cd​e​fg​h​ij​k​l​] The above matrix has four rows and three columns, so it is a 4 x 3 matrix. A vector is a matrix with one column and many rows: ⎡⎣⎢⎢wxyz⎤⎦⎥⎥ [wxyz​] So vectors are a subset ..

ML:Linear Regression with One Variable Model Representation Recall that in regression problems, we are taking input variables and trying to fit the output onto a continuous expected result function. Linear regression with one variable is also known as "univariate linear regression." Univariate linear regression is used when you want to predict a single output value y from a single input value x...

Week 1 Lecture Notes ML:Introduction Where is machine learning used? Introduction : where is machine learning used? - web search engine like Google or Bing -> learned how to rank web pages - Facebook or Apple's photo typing application -> recognizes your friends - spam filter in your email - web click data, also called clickstream data from Silicon Valley companies moreover - applications that c..