geometry - LAPACK: Solving large periodic banded system of equations -

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i have solve large number of simultaneous equations (~1000s) solve @ every time step general mean curvature flow problem. problem defined on closed manifolds boundary condition periodic.

i using successive-over-relaxation algorithm right solve this, slow. tried dgbtrf -> dgbtrs (without periodicity condition), , quite faster.

the coefficient matrix looks this

     ⎛c₁   d₁ e₁        a₁   b₁⎞     ^      ⎢b₂   c₂ d₂ e₂  0       a₂⎥     |      ⎢a₃   b₃ c₃ d₃  .  0      ⎥     |  ← ⎢     a₄ b₄ c₄  .  .      ⎥   ~1000      ⎢      0  .  .  .  .  en₋₂⎥     |      ⎢en₋₁     0  .  .  .  dn₋₁⎥     |      ⎝dn   en        bn  cn ⎠     v

i need solve pentadiagonal systems, not symmetric , not known positive definite.

is there way solve cyclic/periodic banded systems in lapack?

or have use general solvers, such dgetrs?


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