Zhentiw - 博客园

2020年8月17日

[Machine Learning] Octave Computing on Data

摘要： Mutiplate materix: Everytime you see '.' mean element wise operator. >> A = [1 2; 3 4; 5 6]; >> B = [11 12; 13 14; 15 16]; >> C = [1 1; 2 2]; >> A*C a 阅读全文

posted @ 2020-08-17 22:04 Zhentiw 阅读(138) 评论(0) 推荐(0)

[Machine Learning] Octave Moving data around

摘要： Load data: load featuresX.dat who: Check how many variables in your current session: who whos: details about variables: whos Clear one variable: clear 阅读全文

posted @ 2020-08-17 21:36 Zhentiw 阅读(108) 评论(0) 推荐(0)

[Machine Learning] Octave Basic Operations

摘要： You can do baisc math: 5+6 32-8 1/2 2^3 1 == 2 % ans = 0 means false 1 ~=1 % 1 not equals to 2. ans = 1 means true 1 && 0 1 || 0 xor(1, 0) Change the 阅读全文

posted @ 2020-08-17 20:39 Zhentiw 阅读(116) 评论(0) 推荐(0)

2020年8月16日

[Linear Algebra] Inverse and Transpose

摘要： 0 mertix doesn't have inverse. Only square materix (mxm) has inverse Tanspose: % Initialize matrix A A = [1,2,0;0,5,6;7,0,9] % Transpose A A_trans = A 阅读全文

posted @ 2020-08-16 21:04 Zhentiw 阅读(229) 评论(0) 推荐(0)

[Linear Algebra] Matrix-Matrix Multiplication

摘要： The whole idea is to conver matrix-matrix multiplication to matrix-vector multiplication. Not commutative: Identity matrix: % Initialize random matric 阅读全文

posted @ 2020-08-16 20:42 Zhentiw 阅读(229) 评论(0) 推荐(0)

2020年8月15日

[Linear Algebra] Matrix Vector Multiplication

摘要： For example the predicting house pirces example, we can code it in one line for materix vector multiplication. The tip is conver size to a m*2 matrix, 阅读全文

posted @ 2020-08-15 20:52 Zhentiw 阅读(187) 评论(0) 推荐(0)

[Linear Algebra] Matrices and Vectors

摘要： Matrices are 2-dimensional arrays: It's a 4*2 matrix 1 column's matrice is called Vector; % The ; denotes we are going back to a new row. A = [1, 2, 3 阅读全文

posted @ 2020-08-15 20:21 Zhentiw 阅读(132) 评论(0) 推荐(0)

2020年8月13日

[XState] Invoke with callback

摘要： Invoke not only able to return a promise, but also a callback function with 'sendBack' & 'receive' callbacks invoke: { // nested state with id referen 阅读全文

posted @ 2020-08-13 15:56 Zhentiw 阅读(274) 评论(0) 推荐(0)

2020年8月12日

[PostgresSQL] Install and start the service

摘要： Install: brew install postgresql Start: brew services start postgresql psql postgres Create a table: $ postgres=# create table Users ( $ postgres(# cr 阅读全文

posted @ 2020-08-12 15:40 Zhentiw 阅读(148) 评论(0) 推荐(0)

[Node.js] Serve a random static file with Express

摘要： To create a virtual path prefix (where the path does not actually exist in the file system) for files that are served by the express.static function, 阅读全文

posted @ 2020-08-12 02:50 Zhentiw 阅读(108) 评论(0) 推荐(0)

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