Matrix Transformations – Linear Algebra

1. Functions and Transformations

In standard algebra, a function takes a single number as an input and outputs a new number: f(x) = y.

In Linear Algebra, we scale this concept up. A Transformation (often denoted as T) is a mathematical rule that takes an entire Vector as an input and assigns it to a new Vector output. We write this as T(x) = b.

You can think of a transformation as a machine that takes a point in space, moves it according to specific rules, and drops it in a new location.

2. Matrix Transformations

The magic of linear algebra is that every linear transformation can be perfectly represented by a Matrix. By multiplying a coordinate vector by a transformation matrix, we can scale, rotate, reflect, and shear objects in space.

T(x) = A x

Try the interactive visualizer below. Watch how changing the values in the 2×2 Matrix (A) physically alters the “F” shape on the 2D Cartesian plane.

A =
1
0
0
1
F

3. Properties of Matrix Transformations

For a transformation to be considered a mathematically valid Linear Transformation, it must rigidly follow two specific properties. If a matrix represents the transformation, these properties are automatically guaranteed.

Property 1: Additivity (Superposition)

Transforming two vectors added together yields the exact same result as transforming them individually and then adding their results.

T(u + v) = T(u) + T(v)

Property 2: Homogeneity (Scalar Multiplication)

Scaling a vector by a constant (c) and then transforming it is the same as transforming the vector first and then scaling the result.

T(cu) = cT(u)

References

  • Anton, H., & Rorres, C. Elementary Linear Algebra, 11th Edition (pp. 75-83). Wiley.
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