NEWS.md
In GFT: Generalized Fisher Transformation of Correlation Matrices

GFT 1.0.1

inv_gft_newton() gains a safeguard argument, default TRUE. The new default fixes the stall described below. safeguard = FALSE reproduces the previous behaviour, which is the published comparator of Chen, Fei and Yu (2025) with only the Armijo line search added, and is the variant benchmarked in the accompanying paper. Set it when reproducing those results.
With the new default, inv_gft_newton() no longer stalls short of the requested tolerance and returns converged = FALSE on a small fraction of well conditioned problems. Close to the solution the objective f = tr(exp(A)) - sum(x) is flat to within cancellation, so the Armijo test carries no information; the line search then exhausted all of its halvings at every iteration, the fixed-point fallback was taken instead, and the error could lock at a constant value several orders of magnitude above the attainable floor until maxit was reached. Two safeguards that inv_gft() already used have been added: the full Newton step is now taken untested once the predicted decrease falls below the floating-point resolution of f, and a persistent lack of progress near the rounding floor hands the iteration to the (contractive) fixed point.

In a sweep over random correlation matrices at n = 10, the failure rate falls from about 5% to 0, and the worst-case cost from 12,375 eigendecompositions to 6.

The defect was present on all platforms and is not specific to any BLAS or LAPACK build; it surfaced on CRAN's ATLAS check because that arithmetic moved one test matrix into the affected set.

inv_gft(), inv_gft_fp() and inv_gft_broyden() are unchanged. Their results are unaffected by this release.

Removed the single quotes around acronyms and author names in DESCRIPTION, as requested by the CRAN reviewer. Single quotes are now used only for software names.