Array and Matrix
An array is defined by
[Scalar, Scalar, Scalar, Scalar, ..., Scalar] |
An 1D array is usually considered same as a row vector or a matrix with only one row.
An matrix is defined as
[Row; Row; Row; Row; ...; Row] |
where Row is defined as
Scalar, Scalar, Scalar, Scalar, ..., Scalar |
Each of the matrix rows must contains the same number of scalar elements.
After the vector is assigned to a variable, the value of an element of the vector can be accessed by
VECTOR_NAME[i] |
where i is the indices of the array.
The specified element of the vector can also be assigned to another value by
VECTOR_NAME[i] = value |
You can also extract sub-vector from a matrix by
VECTOR_NAME[i1:i2] |
where i1≤i2 is the indices range in the vector.
After the matrix is assigned to a variable, the value of an element of the matrix can be accessed by
MATRIX_NAME[i, j] |
which i is the row number and j is the column number of the matrix.
The specified element of the matrix can also be assigned to another value by
MATRIX_NAME[i, j] = value |
You can also extract sub-matrix from a matrix by
MATRIX_NAME[i1:i2, j1:j2] |
where i1≤i2 is the indices range in rows and j1≤j2 is the indicies range in column.
If a symbol ":" is used for the indices of vector or matrix, it means the range is the whole length of elements for the vector or number of rows/columns for the matrix.
The following are some examples
Input |
Output |
a = [1,2,3,4,5] |
|
a[2] |
|
a[2:4] |
|
a[3:] |
|
a[:2] |
|
a[:] |
|
a[3] = 0 |
|
A=[1,2,3;4,5,6] |
|
A[2,3] |
|
A[1, 2:3] |
|
A[:, 2:3] |
|
A[1:2,2:3] |
|
A[1] |
|
A[1:2] |
|
A[2,2] = 0 |
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