---
title: "Barak A. Pearlmutter"
type: "entity"
entity_kind: "person"
status: "hub"
canonical_name: "Barak A. Pearlmutter"
aliases: ["Barak Pearlmutter","Pearlmutter, Barak A."]
first_seen: "2026-07-07T00:00:00.000Z"
writer_model: "claude-opus-4-8"
connects_to: ["automatic differentiation","Hessian-vector product","computational neuroscience","backpropagation","acoustic source separation"]
source_sha: "d9f55edfacd13bb61915c8838ba71fcdcb45df33001aa3f3579ef105ebe2f930"
seek_code_commit: "f8a723c"
---


Barak A. Pearlmutter is a computer scientist and computational neuroscientist
at Maynooth University (Brain and Computation Lab; formerly Siemens Corporate
Research and the University of New Mexico, with joint neuroscience and
electrical-engineering appointments) whose work runs across automatic
differentiation, neural networks, acoustic source separation and localization,
and programming-language design — his own homepage lists his interests as
"adaptive systems, neural Networks, how the brain works, machine learning,
acoustic source separation and localization, neuroscience, programming language
design," and he is also a practicing ceramic artist. His 1994 paper "Fast Exact
Multiplication by the Hessian" introduced the differential R-operator now known
as "the Pearlmutter trick."

Within this vault Pearlmutter is the second author of the JMLR 2018 survey
(Baydin, Pearlmutter, Radul & Siskind) that anchors much of
[[moc-backpropagation-origins]] and the claim
[[claim-ml-and-ad-communities-mutually-unaware]] — a citation the vault leaned on
constantly before it ever examined the person behind it. His own cross-field
career is a personal instance of the disciplinary bridging that survey both
documents and performs.

## References

- [[claim-ml-and-ad-communities-mutually-unaware]] — the mutual-unawareness
  claim resting on the survey he co-authored.
- [[claim-backpropagation-special-case-of-reverse-mode-ad]] — the survey's
  backprop-as-reverse-mode-AD identity, also co-authored by him.
- [[claim-pearlmutter-1994-r-operator-exact-hessian-vector-product]] — his 1994
  exact Hessian-vector-product trick, still named infrastructure decades on.
- [[observation-ad-survey-second-author-personally-spans-ml-ad-divide]] — the
  observation that the survey's own authorship spans the divide it describes.