LBFGS Settings

[PBrdng]

Manopt’s default WolfePowellLinesearch() uses a very strict curvature condition and no finite lower step-size threshold.
For some CPD/L-BFGS cases, this caused the solver to appear not to start because it was stuck inside a single line-search step before the progress meter could advance.

Patch Notes

• Configured the default L-BFGS Wolfe line search explicitly instead of using raw Manopt defaults.
• :wolfe now uses sufficient_curvature = 0.9, stop_when_stepsize_less = 1e-8, stop_decreasing_at_step = 100
• Removed unsupported/fragile line-search exposure. :hagerzhang is only accepted if the installed Manopt version actually defines HagerZhangLinesearch.
• Fixed some more inconsistencies in the code.

a, b, c, d = 2,2,2,2
r = 3
A = reshape(sum(kron(randn(d), randn(c), randn(b), randn(a)) for _ in 1:r), a, b, c, d);
cpd(A, r; tol = 1e-8, normalized_objective = false)
cpd(A, r; solver = :lbfgs, tol = 1e-8)

now advances normally.