Linear Algebra Intermediate

Matrix Norms Calculator

Compute the Frobenius norm ‖A‖_F, 1-norm (max column sum), ∞-norm (max row sum), and 2-norm (largest singular value / spectral norm). Every formula is computed step by step.

Subject: Linear Algebra
Input: 2×2 or 3×3 matrix
Output: 4 norms + bar chart
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Matrix Input
Result
Enter matrix values and click Compute Norms

Step-by-Step Work

Which Norm Should You Use?
‖A‖_F = √(Σ aᵢⱼ²)

The Frobenius norm treats the matrix as a long vector — easy to compute, great for optimization. The spectral norm (2-norm) measures the worst-case amplification factor of A on any vector and equals its largest singular value.

The 1-norm is the max absolute column sum; the ∞-norm is the max absolute row sum. Both are easy to compute by hand.

Exam tip — for condition numbers and error analysis, the spectral norm is standard. For deep learning, the Frobenius norm is most common.
Norm Inequalities
  • ‖A‖₂ ≤ ‖A‖_F ≤ √n · ‖A‖₂
  • ‖A‖₂ ≤ √(‖A‖₁ · ‖A‖∞)
  • ‖AB‖ ≤ ‖A‖ · ‖B‖ (submultiplicativity)
  • ‖A‖₂ = σ_max (largest singular value)

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