Michael Chen wrote: > --this is my first version for the purpose of storing sparse numerical > matrix in sql > --please let me know how to fix the bug at the end of the file, and how to > tune the performance > --or any better reference, thanks! > > .explain -- return result in more readable > format > .echo on -- echo the sql stmnt > > --I plan to store my sparse matrix (3 x 4) in table like this: > -- [ 1 2 0 0 ] > -- [ 0 3 9 0 ] > -- [ 0 1 4 0 ] > A sparse matrix can be stored in a table like
CREATE TABLE Matrix ( Row INTEGER NOT NULL, Col INTEGER NOT NULL, Value REAL, PRIMARY KEY (Row, Col) ); With this representation, arithmetic on matrices can be done as: -- MatrixA + MatrixB SELECT Row, Col, SUM(Value) AS Value FROM (SELECT * FROM MatrixA UNION ALL SELECT * FROM MatrixB) GROUP BY Row, Col; -- MatrixA - MatrixB SELECT Row, Col, SUM(Value) AS Value FROM (SELECT * FROM MatrixA UNION ALL SELECT Row, Col, -Value FROM MatrixB) GROUP BY Row, Col; -- MatrixA * MatrixB SELECT MatrixA.Row AS Row, MatrixB.Col AS Col, SUM(MatrixA.Value * MatrixB.Value) AS Value FROM MatrixA INNER JOIN MatrixB ON MatrixA.Col = MatrixB.Row GROUP BY Row, Col; _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
