What is preconditioning in optimization?

Updated May 16, 2026

Short answer

Preconditioning transforms gradients to improve convergence speed.

Deep explanation

Preconditioning rescales gradients using a transformation matrix that compensates for poor curvature. It effectively reshapes the loss surface into a more isotropic form, improving Gradient Descent efficiency.

Real-world example

Used in large-scale linear regression and scientific computing.

Common mistakes

  • Applying preconditioning without understanding scaling effects.

Follow-up questions

  • What is diagonal preconditioning?
  • How is it related to Adam?

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