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tools:matrix:start [2017/03/17 12:31]
graf [Accessing Elements]
tools:matrix:start [2022/04/20 13:29] (current)
ursgraf [Logging Matrices]
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 The blocks in the control system are connected among each other with the aid of signals. As described in [[eeros_architecture:control_system:signals|]] they carry a timestamp and a value. The value could be a simple type such as an integer or float. Quite often it will consist of a vector or a matrix. A three dimensional vector of type ''double'' can be declared and initialized as follows: The blocks in the control system are connected among each other with the aid of signals. As described in [[eeros_architecture:control_system:signals|]] they carry a timestamp and a value. The value could be a simple type such as an integer or float. Quite often it will consist of a vector or a matrix. A three dimensional vector of type ''double'' can be declared and initialized as follows:
 <code cpp> <code cpp>
-  Vector<3, double> v;  +Vector<3, double> v; 
-  v << 1.5, -2, 0;+
 </code> </code>
 The declaration could be simplified to  The declaration could be simplified to 
 <code cpp> <code cpp>
-  Vector3<> v;  +Vector3<> v; 
-  v << 1.5, -2, 0;+
 </code> </code>
-as ''Vector3'' is a predefined type with three dimensions and the default element type is ''double''. A matrix of 3 times 3 with element type ''int'' could be defined as+as ''Vector3'' is a predefined type with three dimensions and the default element type is ''double''. A ''Vector3'' is identical to the type ''Matrix<3,1,double>''. The vector could be initialized as follows
 <code cpp> <code cpp>
-  Matrix<33int> m;  +v = {1.5-20} 
-  << 1, 47, +<< 1.5-20; // or with input operator 
-       2, 5, 8, +Vector3 v{1,2,3}// or directly upon declaration
-       3, 6, 9;+
 </code> </code>
 +A matrix of 3 times 3 with element type ''int'' could be defined as
 +<code cpp>
 +Matrix<3, 3, int> m; 
 +m << 1, 2, 3,
 +     4, 5, 6,
 +     7, 8, 9;
 +</code>
 +The first three numbers will be filled into the first row. While the internal representation is simply a one dimensional vector, the matrix could be visualized as 
  
 +| ^col0^col1^col2^
 +^row0|1|2|3|
 +^row1|4|5|6|
 +^row2|7|8|9|
 +When declaring and initializing a matrix, the values must be given colon per colon. The same matrix as given above would be initialized as follows 
 +<code cpp>
 +Matrix<3, 3, int> m{1, 4, 7, 2, 5, 8, 3, 6, 9};
 +</code>  
 ===== Accessing Elements ===== ===== Accessing Elements =====
 You can access rows, columns or single elements of matrices with the following methods: You can access rows, columns or single elements of matrices with the following methods:
 <code cpp> <code cpp>
-m.get(0,0);  // will return element, 0 +m.get(0,0);  // returns element, 1 
-m.getRow(1);  // will return row, [2,5,8+m.get(1,0);  // returns element, 4 
-m.getCol(0);  // will return column, [2,5,8]+m.getRow(1);  // returns row, [4,5,6
 +m.getCol(0);  // returns column, [1,4,7]' 
 +m.getSubMatrix<2,2>(0,1);   // returns matrix [[2,5][3,6]] 
 +</code> 
 +Single elements, rows or columns can be written with the methods //set()//, //setRow()//, or //setCol()//.  
 + 
 +The operators () and [] work as well as can be seen by the following example 
 +<code cpp> 
 +m(3);   // returns element or sets element with index 3  
 +m[3];   // returns element or sets element with index 3  
 +m(2,1);   // returns element or sets element with index 7 
 +m[2,1];   // does not work, as the [] operator cannot be defined for two parameters 
 +</code> 
 + 
 +===== Logging Matrices ===== 
 +A matrix can be logged simply by writing 
 + 
 +<code cpp> 
 +log.info() << m; 
 +</code> 
 +With the 3 x 3 matrix from above we would get 
 +<code> 
 +2021-09-16 17:36:53:929    I:  [ [1 4 7]' [2 5 8]' [3 6 9]' ] 
 +</code> 
 +The matrix is plotted colon per colon. To give some more examples: 
 +<code cpp> 
 +Matrix<1,1> m1{1}; 
 +Matrix<2,1> m2{1,2}; 
 +Matrix<1,2> m3{1,2}; 
 +</code> 
 +This matrices will be printed as  
 +<code> 
 +2021-09-16 17:37:18:122    I:  [1]' 
 +2021-09-16 17:37:18:122    I:  [1 2]'         // one colon with two rows 
 +2021-09-16 17:37:18:122    I:  [ [1]' [2]' ]' // one row with two colons 
 +</code> 
 + 
 +===== Matrix Operations ===== 
 +Some examples show basic matrix operations. 
 +<code cpp> 
 +Vector2 v1{1,2}; 
 +Matrix<1,2> v2{3,4}; 
 +log.info() << v1 * v2;            // will print [ [3 6]' [4 8]' ] 
 +log.info() << v2 * v1;            // will print [11]' 
 + 
 +Matrix<2,2,double> m1{1,1.5,-1,2}; 
 +log.info() << v2 * m1;            // will print [ [9]' [5]' ] 
 +log.info() << v1.transpose() * m1;// will print [ [4]' [3]' ] 
 + 
 +auto x = v2 * m1; 
 +Vector2 v4 = x.transpose(); 
 +log.info() << v4;                 // will print [9 5]' 
 +</code>
tools/matrix/start.1489750262.txt.gz · Last modified: 2017/03/17 12:31 by graf