Version 0.2.1 #48

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Release notes:

New features

• Second derivatives of the unknown, test and trial functions (∇∇(u), ∇(∇(u)), Δ(u)) are compiled by the kernels, with Gridap's layout (TensorValue{D,D}; ThirdOrderTensorValue{D,D,N} with H[a,b,k] = ∂²u_k/∂x_a∂x_b). They are exact also on non-affine quadrilaterals and hexahedra (curvature of the cell map included), where Gridap's ∇∇ is not defined. Supported in the residual, the assembled Jacobian and the matrix-free Jacobian. ∇∇ of FE functions that are not the unknown is read from their nodal values. ∇∇ on skeleton integrals and of H(div) fields goes to the Gridap fallback.
• Hybrid fallback by triangulation: an integral the engine cannot translate (e.g. ∇(u*w)) now sends only the integrals of its triangulation to Gridap, instead of the whole weak form.
• Cheap update: forms with the same structure as the operator's (same measures, operations and constants up to their values, same FE functions) rebind the compiled groups. Code, tables, colouring, sparsity pattern, linear maps and auxiliary buffers are reused, and nothing is compiled or allocated per cell per load step. The same applies to KernelFunctional. HFK_CHECK_REBIND=1 checks the fast path against a full compilation; HFK_DEBUG_UPDATE=1 prints the path taken and its timings.

Fixes

• Numbers in the integrand are read as run-time parameters also on simplexified meshes.
• FE functions in the form are identified by their dof vectors, so the same function used several times in a form is evaluated once, also on sub-triangulations.
• HFK_DEBUG_LINEAR is read at run time.

No breaking changes; HyperFEM's [compat] HyperFEMKernels = "0.2" covers this release.