b2KIT

Linear Transformation Visualizer

See how 2x2 matrices transform the plane. Drag basis vectors and watch the grid deform. Shows determinant, eigenvalues, and SVD.

Tested tool guide Tested browser tools Checked August 16, 2026

What Linear Transformation Visualizer does, with a checked example

Choose a 2x2 matrix or drag the transformed basis vectors to see the corresponding linear map. The visualizer moves the coordinate grid and reports the determinant, eigenvalues, and singular value decomposition associated with that map. It is useful for connecting matrix entries to geometry rather than reading the numbers in isolation. A common mistake is treating the matrix rows as basis-vector endpoints. Under the usual column-vector convention, its columns are where the standard basis vectors land.

Worked example

A concrete input and expected output from the current implementation.

Input

Matrix [[2, 0], [0, 1]]

Expected output

e1 maps to (2, 0), e2 maps to (0, 1), determinant = 2, eigenvalues = 2 and 1, and singular values = 2 and 1. The grid is stretched horizontally by a factor of 2 and is unchanged vertically.

The transformation sends (x, y) to (2x, y). A unit square becomes a 2-by-1 rectangle, so its area is multiplied by 2; the two coordinate axes are also eigenvector directions with scale factors 2 and 1.

How the result is produced

1

Mapping the plane

For A = [[a, b], [c, d]], each point (x, y) maps to (ax + by, cx + dy). The first column is the image of e1 = (1, 0), and the second is the image of e2 = (0, 1). Grid lines remain straight, parallel lines remain parallel, and the origin remains fixed, although the plane can collapse onto a line or point.

2

Reading the invariants

The determinant ad - bc is the signed area scale: its magnitude gives area change, its sign records orientation, and zero indicates collapse to lower dimension. Eigenvalues describe scale factors along corresponding eigenvector directions. The SVD writes the matrix as U Sigma V^T, separating orthogonal changes of direction from the nonnegative axis stretches listed in Sigma.

Good uses

  • Checking whether a proposed 2x2 matrix represents a rotation, reflection, shear, directional scale, or singular collapse.
  • Teaching why matrix columns are transformed basis vectors and how their positions determine the rest of the deformed grid.
  • Comparing determinant, eigenvalues, and singular values for a matrix whose visible stretching is difficult to infer from its entries.

Limits and checks

  • The determinant measures signed area change, not the length multiplier of every vector. Different directions can change length by different amounts.
  • Eigenvalues and singular values answer different questions. Eigenvalues may be negative or complex, while singular values are always real and nonnegative.
  • SVD factors are not always unique. Signs can be exchanged between matching singular vectors, and repeated or zero singular values permit additional valid choices.

Common questions

Does determinant zero mean every point is sent to the origin?

No, not necessarily. A nonzero 2x2 matrix with determinant zero can have rank one, sending the entire plane onto a single line through the origin. Only the zero matrix sends every vector to the origin. The deformed grid may therefore appear flattened into a line rather than reduced to one point.

Why can the eigenvalues differ from the stretches visible in the grid?

Eigenvalues measure scaling only along eigenvector directions, which need not be perpendicular and may not exist as real directions. Singular values measure the largest and smallest orthogonal stretch factors of the whole transformation. For a shear, the eigenvalues can both equal 1 even though some vectors visibly lengthen and the singular values differ from 1.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.

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