Repository owner: Jacob Williams (jacobwilliams)

qdldl-fortran

Sparse LDL-transpose factorization, orderings and solves for quasi-definite systems.

Repository · Pinned source (8ebdd7fa1075) · Try in playground · Checked package example

GAMS classifications

About this package

Category: Linear algebra
License: Apache-2.0

Topics: fortran, fortran-package-manager, ldl-factorization, ldlt-factorization, linear-algebra, linear-systems, matrix-ordering, numerical-optimization, quasi-definite, sparse-data, sparse-linear-algebra, sparse-linear-systems

Package dependencies

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Build record verified 2026-10-28.

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Reviewed procedures

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qdldl_type%analyze / factor / solve

Module: qdldl_module

D2b4

D2b4: verified

Derivatives / callbacks: not applicable

Sparse symmetric quasi-definite systems; no general-indefinite or pivoting guarantee is inferred. Natural, RCM and AMD orderings are checked. The checked driver solves two known right-hand sides, checks finite results and successful termination, and independently recomputes the residual and scaled normwise backward error.

Pinned source: src/qdldl_module.f90

Author examples/tests: example/example_kkt.f90

Load checked GAMS driver: gams-qdldl-quasidefinite-solve