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Course material


Slides (from class)



Lecture notes


Some suggested textbooks:

-G. Strang, Inroduction to Linear Algebra, Wellesley-Cambridge Press, 2016.
-E. Carlini, LAG: the written exam, CLUT 2019.
Office hours:

  by appointment only, send me an email at ada.boralevi(AT)polito.it


Lectures' log (geometry), a.y. 2023-2024

Lecture

Date

Contents

Reference to notes and more

1 3/5 Matrices with real coefficients. Opposite and transpose of a matrix, properties. Square matrices: diagonal, triangular, symmetric, skew-symmetric. Linear algebra on a number field different from R. 1.1, 1.2
2.3
2-3 3/6 Matrix addition and scalar multiplication: definition and properties, examples. Product of matrices: definition and examples. Properties of the product of matrices. Invertible matrices and their properties: inverse of the transpose and the product, examples.
Linear equations and linear systems. Matrices associated to a linear system and matrix form.
2.1, 2.2
3.1

4 3/8 Linear equations, linear systems, solutions, associated matrices, examples. Homogeneous and compatible systems. Elementary row operations, pivots, row-echelon form. Equivalent matrices and equivalent linear systems. Examples of Gauss reduction.
3.1, 3.2
4.1


3/11 Exercise session led by Dr. Canino
5 3/12 Rank of a matrix. Examples and exercises on row reduction and rank computation. Solving a linear system: equivalent systems have equivalent associated matrices, Rouché-Capelli theorem, examples.

4.2
5.1
Homework solution
6-7 3/13 Matrix equations and solutions: computation of inverse matrix via row reduction. Invertible matrices have maximal rank. Row and column rank, rank of the transpose. Examples.
Determinants: submatrices, cofactors, examples. Laplace expansion along rows and columns. Determinant of the transpose matrix. Binet's theorem. Invertible matrices have nonzero determinant. Adjugate and cofactor matrix, computation of the inverse matrix using the adjugate, examples.
5.2, 5.3
6.1, 6.2, 6.3


8 3/19 Geometric vectors: segments, applied vectors, direction, orientation and length of a vector. Parallel and coplanar vectors. Cartesian systems of coordinates. Operations on vectors: sum and the parallelogram rule.

Quizzes on matrices and linear systems (quizzes file 1 without solutions).
71. 7.3, half of 7.4


9-10 3/20 Sum and difference of vectors, multiplication by a scalar, properties and geometric interpretation. Normalization of a vector. Characterization of parallel and coplanar vectors through rank. Dot (scalar) product: definition, examples, properties. Dot product and angles: parallel and orthogonal vectors. Chauchy-Schwartz and triangle inequality. Orthogonal projection. Examples and exercises.
7.4, 7.5
8.1


3/25 Exercise session led by Dr. Canino
11-12
3/27 Cross (vector) product: definition, geometric interpretation, properties, examples. Cross product and area of a triangle. Mixed product and volume of a tetrahedron. Some exercises on vectors.

Parametric equations of lines and planes in space, examples.
8.2, 8.3
9.1, 9.2


3/28-4/3: Easter break

13
4/9 Relative position of two lines in space. Cartesian equations of planes in space; switching from parametric to Cartesian equation and backwards. Examples and exercises.
9.1
10.1
14-15
4/10 Relative position of two planes in space and Cartesian equations of lines; switching from parametric to Cartesian equation and backwards. Relative position of linear objects in the space: a line and a plane and 2 lines. Examples and exercises.


10.2, 10.3
Homework solution


4/15 Exercise session led by Dr. Canino
16 4/16
Distance between two sets, definition. Distance of a point from a plane and from a line, examples.
11.1, 11.2
17-18 4/17
Distance of a plane from another plane and from a line, examples. Distance between two skew lines, examples.
Introduction to vector spaces.

Quizzes on lines and planes and distances (quizzes file 3 without solutions).
11.3, 11.4
Introduction to 12.1

19-20 4/24 Vector spaces and subspaces: definition, properties, examples. Union and intersection of subspaces, sum of subspaces, examples. Linear combinations, generators, finitely generated vector spaces: definitions and examples.
12.1, 12.2, 12.3
13.1
21 4/26 Linear combinations, generators, span of a set of vectors: more examples. Linearly dependent and independent vectors, examples. Introduction to the discarding algorithm.


13.1,13.2
Part of 14.1



4/27: Midterm #1


4/29 Exercise session led by Dr. Canino
22 4/30 The discarding algorithm, examples. Bases and components with respect to a basis, examples. 14.1, 14.2


5/1: May Day

23 5/7
Extract a basis from a set of generators and complete a set of independent vectors to a basis. Number of vectors in a basis and dimension of a vector spaces, examples. Dimension of subspaces, examples.

14.2
15.1, 15.2
Homework solution
24-25 5/8
Examples of computation of dimension of subspaces. Grassmann formula, direct sum. Dimension and matrix rank: row and column space of a matrix. Linear maps: definition, examples, some properties. Definition of Kernel and Image.
15.3, 15.4
16.1

5/13 Exercise session led by Dr. Canino
26 5/14
Some more examples of linear maps. Linear maps K^n-->K^m and their associated matrices.

Quizzes on vector spaces (file 4 without solutions) .
16.1

27-28 5/15
More on linear maps K^n-->K^m and their associated matrices, kernel, image and rank. Isomorphisms, isomorphic vector spaces, invertible matrices, examples. Linear maps for finitely generated vector spaces, examples.


16.2, 16.3, 16.4
17.1

29
5/21
Linear maps for finitely generated vector spaces, matrix associated to a linear map: definition and examples. Dimension theorem: kernel, image and rank of the associated matrix. Introduction to matrix of change of basis.
17.2

30-31
5/22
Matrix associated to the composition of linear maps and to the inverse. Endomorphisms. Matrix of change of basis, examples. Eigenvalues, eigenvectors, eigenspaces, characteristic polynomial: definition, properties, how to find them, examples.

Informal notes on change of basis in a vector space (you can only read sections 1 2 and 3 so far!)
17.3
18.1, 18.2


32-33
5/29
Algebraic and geometric multiplicity of eigenvalues. Diagonalizable matrices. Similar matrices. Symmetric matrices are diagonalizable. Cayley-Hamilton theorem and eigenvalues of nilpotent matrices. Examples and exercises on diagonalization.
19.1, 19.2, 19.3


34
5/31
Inner products (dot products), definition and examples.

Quizzes on linear maps, associated matrices, diagonalization (file 5 without solutions).
20.1



6/1: Midterm #2


6/3 Exercise session led by Dr. Canino
35
6/4
Inner products: Cauchy-Schwartz and triangle inequality. Orthogonal and orthonormal sets and bases. Gram-Schmidt orthonormalization algorithm, examples. Special and non-special orthogonal matrices.

20.1, 20.2, 20.3

36-37
6/5
Orthonormal diagonalization for symmetric matrices.
Quadratic forms and symmetric matrices, positive/negative definite/semidefinite, indefinite forms. Descartes' rule of signs.
20.4
21.1, 21.2
38
6/7
More on quadratic forms and their character of definition, with examples.
Conics in their canonical form: hyperbola, ellipse, parabola.
21.2
22.1

6/10 Exercise session led by Dr. Canino
39
6/11
Conics and rototranslations in the Euclidean plane. Reduction of a conic in its canonical form. Classification of degenerate and non-degenerate conics.


22.2
23.1, 23.2

40-41
6/12
Classification of degenerate and non-degenerate conics, examples. Introduction to quadric surfaces. 

Quizzes on quadratic forms, conics, orthogonal diagonalization (file 6 without solutions)

Solutions of exam simulation #4
23.2






x2