Linear Transformations#
Solution to Exercise 6.1
(a) Let \(\vec{u} = (u_1, u_2)^\mathsf{T}, \vec{v} = (v_1, v_2)^\mathsf{T} \in \mathbb{R}^2\) and \(\alpha \in \mathbb{R}\)
therefore \(T\) is a linear transformation.
(b) \(T\) is not a linear transformation since
(c) Let \(\vec{u} = (u_1, u_2)^\mathsf{T}, \vec{v} = (v_1, v_2)^\mathsf{T} \in \mathbb{R}^2\) and \(\alpha \in \mathbb{R}\)
therefore \(T\) is a linear transformation.
(d) Let \(\vec{u} = (u_1, u_2, v_3)^\mathsf{T},\vec{v} = (v_1, v_2, v_3)^\mathsf{T}\in \mathbb{R}^3\) and \(\alpha \in \mathbb{R}\)
therefore \(T\) is a linear transformation.
(e) \(T\) is not a linear transformation since
(f) Let \(u = f(x), v = g(x) \in P(\mathbb{R})\) and \(\alpha \in \mathbb{R}\):
therefore \(T\) is a linear transformation.
(g) Let \(u = f(x), v = g(x) \in P(\mathbb{R})\) and \(\alpha \in \mathbb{R}\):
therefore \(T\) is a linear transformation.
Solution to Exercise 6.2
The transformation matrix is
Calculating \(T \begin{pmatrix} 2 \\ 5 \end{pmatrix}\)
therefore \(T\begin{pmatrix} 2 \\ 5 \end{pmatrix} = \begin{pmatrix} 13 \\ -18 \end{pmatrix}\).
Solution to Exercise 6.3
The transformation matrix is
so the inverse is
Therefore
Solution to Exercise 6.4
The transformation matrix is determined using equation (6.2) which is
Using Gauss-Jordan elimination to calculate the inverse of \((\vec{u}_1, \vec{u}_2, \vec{u}_3)^{-1}\)
So \((\vec{u}_1, \vec{u}_2, \vec{u}_3)^{-1} = \begin{pmatrix} -1 & -2 & 1 \\ 1 & 1 & 0 \\ -2 & -2 & 1 \end{pmatrix}\) and
Checking \(A\)
Solution to Exercise 6.5
The transformation matrix is
therefore
Solution to Exercise 6.6
The transformation matrix is
therefore
Solution to Exercise 6.7
(a) \(\begin{pmatrix} 2 & 4 & 4 & 2 \\ 1 & 1 & 3 & 3 \\ 1 & 1 & 1 & 1 \end{pmatrix} \)
(b) Translate by \((-3, -2)^\mathsf{T}\) so that the centre of the square is at the origin:
Rotate by \(\pi/3\) clockwise about the origin:
Translate by \((3, 2)^\mathsf{T}\) so that the centre of the square is back to \(\vec{c}\)
(c) Calculate composite alignment matrix
Apply composite transformation matrix