---
title: "Bert Speelpenning"
type: "entity"
entity_kind: "person"
status: "hub"
canonical_name: "Bert Speelpenning"
aliases: ["Bert A. Speelpenning","Bernt Speelpenning"]
first_seen: "2026-07-07T00:00:00.000Z"
writer_model: "claude-sonnet-5"
connects_to: ["reverse-mode automatic differentiation","automatic differentiation (compiler-optimization line)","Seppo Linnainmaa","Andreas Griewank"]
seek_code_commit: "379c8e7"
---


Computer scientist whose 1980 University of Illinois PhD thesis gave the first fully automatic software implementation of reverse-mode automatic differentiation, arrived at independently via compiler optimization rather than via [[entity-seppo-linnainmaa|Seppo Linnainmaa]]'s earlier numerical-analysis line. Matters to this vault as the clearest single case of the AD field's own internal mutual-unawareness: the thesis that first automated the technique does not cite the mathematician who first described it a decade earlier.

## References
- [[claim-speelpenning-1980-does-not-cite-linnainmaa]]
- [[claim-wengert-list-named-for-forward-mode-inventor]] — the "Wengert list" tape his implementation popularized is named for the *forward*-mode inventor, not for him
- [[claim-chainqueen-2019-full-reference-list-omits-ad-discovery-citations]] · [[claim-bolliger-2025-reference-list-omits-ad-discovery-names-names-jax-and-chainqueen]] · [[claim-difftaichi-2020-names-griewank-and-wengert-but-not-linnainmaa-or-speelpenning]] — added 2026-10-09: three further differentiable-physics papers (ChainQueen, Bolliger et al., DiffTaichi) computing the operation his thesis automated, none naming him
- [[claim-griewanks-name-reaches-differentiable-physics-literature-further-than-linnainmaas-or-speelpennings]]
- Captures: 10-inbox/raw/20260707-0924-speelpenning-1980-thesis-compiling, 10-inbox/raw/2026-10-05-does-chainqueen-2019-or-bolliger-et-al-2025.md