affinePart -- Replaces columns in a matrix with an identity matrix

Synopsis

Usage:

affinePart(M,L)

affinePart(M,n)
Inputs:
- M, a matrix,
- L, a list,
- n, an integer,
Outputs:
- a matrix,

Description

Given an n\times m matrix M, with n<m, and a subset L\subseteq\{0,\dots,m-1\}\ of size n, this function replaces the columns with index L by an identity matrix.

i1 : S=ZZ[a_1..a_8];

i2 : M=matrix{toList(a_1..a_4),toList(a_5..a_8)}

o2 = | a_1 a_2 a_3 a_4 |
     | a_5 a_6 a_7 a_8 |

             2      4
o2 : Matrix S  <-- S

i3 : affinePart(M,{0,2})

o3 = | 1 a_2 0 a_4 |
     | 0 a_6 1 a_8 |

             2      4
o3 : Matrix S  <-- S

Ways to use affinePart :

affinePart(Matrix,List)
affinePart(Matrix,ZZ)

For the programmer

The object affinePart is a method function.

affinePart -- Replaces columns in a matrix with an identity matrix

Synopsis

Description

See also

Ways to use affinePart :

For the programmer