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linalg::col -- extract columns of a matrix

Introduction

linalg::col(A, c) extracts the c-th column vector of the matrix A.

Call(s)

linalg::col(A, c)
linalg::col(A, c1..c2)
linalg::col(A, list)

Parameters

A - an m x n matrix of a domain of category Cat::Matrix
c - the column index: a positive integer <= n
c1..c2 - a range of column indices (positive integers <= n)
list - a list of column indices (positive integers <= n)

Returns

a single column vector or a list of column vectors; a column vector is an m x 1 matrix of category Cat::Matrix(R), where R is the component ring of A.

Related Functions

linalg::row, linalg::delCol, linalg::delRow, linalg::setCol, linalg::setRow

Details

Example 1

We define a matrix over Q:

>> A := Dom::Matrix(Dom::Rational)(
     [[1, 1/5, 2], [-3/2, 0, 5]]
   )
                            +-              -+
                            |    1,  1/5, 2  |
                            |                |
                            |  -3/2,  0,  5  |
                            +-              -+

and illustrate the three different input formats for linalg::col:

>> linalg::col(A, 2)
                                 +-     -+
                                 |  1/5  |
                                 |       |
                                 |   0   |
                                 +-     -+
>> linalg::col(A, [2, 1, 3])
                   -- +-     -+  +-      -+  +-   -+ --
                   |  |  1/5  |  |    1   |  |  2  |  |
                   |  |       |, |        |, |     |  |
                   |  |   0   |  |  -3/2  |  |  5  |  |
                   -- +-     -+  +-      -+  +-   -+ --
>> linalg::col(A, 2..3)
                         -- +-     -+  +-   -+ --
                         |  |  1/5  |  |  2  |  |
                         |  |       |, |     |  |
                         |  |   0   |  |  5  |  |
                         -- +-     -+  +-   -+ --




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