Alphabeta Math
DefinitionDefinition: Literature-sourcedProof: Not applicablePipeline-generated
How statement and proof provenance work

The first chip identifies the source of the statement or construction; the second identifies the source of its local proof or verification.

  • Literature-sourced: the exact statement appears in a cited source; only wording and notation differ.
  • AI-adapted: a semantically identical restatement of literature-sourced material, modulo indexing, notation, and boundary cases adopted by the library.
  • AI-generated: a genuinely novel statement formulated by AI, with no source for the claim itself.

These labels describe origin, not correctness: citations and verification chips remain separate evidence.

Forward and central finite-difference Jacobian-vector and Hessian-vector products

Definition

Let m,n≥1, U⊆Rn be open, x∈U, F:U→Rm, f:U→R, and let v∈Rn. Use the Jacobian JF(x) and gradient ∇f(x) of The Jacobian matrix of partial derivatives and the gradient in the scalar-valued case, the Hessian Hf(x) of The Hessian matrix and critical points of a scalar field, and the published Euclidean vector norm ∥⋅∥2 of The p-norms ∥x∥p for rational p≥1, and ∥x∥∞. The Jacobian-vector products below require JF(x) to exist, and the Hessian-vector products require Hf(x) to exist. Each gradient-difference Hessian-vector estimate also requires ∇f to exist at every point in its stencil. The exact products are JF(x)v and Hf(x)v, respectively.

For h>0 with the required points in U, define the forward and central Jacobian-vector estimates

Jh+(F,x,v):=F(x+hv)−F(x)h,Jh0(F,x,v):=F(x+hv)−F(x−hv)2h,

and the gradient-difference Hessian-vector estimates

Hh+(f,x,v):=∇f(x+hv)−∇f(x)h,Hh0(f,x,v):=∇f(x+hv)−∇f(x−hv)2h.

For each requested vector value z(y), write an inexact evaluation as z^(y)=z(y)+e. When an error bound is specified, it is per call: ∥e∥2≤δ for that call's δ≥0. Errors may be dependent or random; a stated bound on a random error is understood to hold almost surely. Define the inexact estimates by substitution:

J^h+(F,x,v):=F^(x+hv)−F^(x)h,J^h0(F,x,v):=F^(x+hv)−F^(x−hv)2h,

H^h+(f,x,v):=∇f^(x+hv)−∇f^(x)h,H^h0(f,x,v):=∇f^(x+hv)−∇f^(x−hv)2h.

Depends on

Used by

Dependency tree · two levels

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Sources