Module: MSolve

Module: MSolve#

Semi-implicit thin film solver for second order differential equations of form:

\[ \frac{\eta}{\Delta t} - G_{ij} \eta_{,ij}= rhs \]

Name: mod_mupro_msolve
Depends on: mod_mupro_base, mod_mupro_fft, mod_mupro_log
Defined variables: None
Defined types: - type_mupro_MsolveContext - type_mupro_MsolveSolveContext
Defined subroutines: - mupro_msolve_setup - mupro_msolve_solve

Defined Types#

type_msolve

Variable	Type	Dimension
Mmsolve,Vmsolve,Ymsolve	real64	dimension(:, :, :, :)
delop	real64	dimension(:, :, :, :)
bc	complex real64	dimension(:, :, :, :)
BCTop,BCBot	int32	-

type_mupro_MsolveContext#

Variable	Type	Dimension	Meaning
gradient_coefficient	real64	(3)	Gradient coefficient
BCTop	int32	-	BC for film surface
BCBot	int32	-	BC for film substrate interface
sysArray	type_msolve	-	Necessary information for the solver

type_mupro_MsolveSolveContext#

Variable	Type	Dimension	Meaning
rin	real64	(z,y,x)	The right hand side of the equation
pout	real64	(z,y,x)	The evolved order parameter distribution
dt	real64	-	Marching step for each simulation
sysArray	type_msolve	-	sysArray from the msolve_setup

The validator contract (added 2026-08-06, T2)#

Both context types carry a status-returning validator alongside the terminating guards (mupro_require_fft, the PR-025c binding preconditions):

context%validate_setup(status) on type_mupro_MsolveContext (msolve.f90:689). Checks what setup_mpi_msolve actually reads: an associated sysArray (the state is allocated on the caller’s target — the PR-025 UB), not-already-set-up (Mmsolve allocation is unconditional), the FFT extents and both wave-vector sets (3D for delop, 2D for rmk), a film of nonzero thickness (dz > 0, k2 > k1 — (hh1-hh2)**3 divides), a finite positive dt (it divides under a square root, and an infinite dt passes > 0 while sending rmk to zero, which then divides as rmk**4), finite gradient coefficients, not-all-zero (the context default meaning “no material”), and gradient_coefficient(3) > 0 (divides under the root).
context%validate_solve(status) on type_mupro_MsolveSolveContext (msolve.f90:817). Checks what msolve_mpi reads: a live FFT plan and its plate-solution coefficients, mqk3_3, at least four film layers (k2 - k1 >= 3 — the one-sided stencils read rin(k1..k1+3) and rin(k2-3..k2); for interior films they merely cross the boundary and produce meaningless numbers rather than crashing, which is why the refusal wording names the geometry), bound rin/pout with the local slab shape, a state that came from the setup (allocated arrays, dt > 0, d33 > 0 — both divide), state shapes matching the current grid, the legacy-dt agreement (tolerance 1.0e-12, mirrored from the solve’s own guard), and the BC flags in 1…4 — checked here and not at setup, because setup only copies them while the solve dispatches on them with a terminating else.

Deliberately unchecked, each awaiting the owner (see TASK.md): negative gradient_coefficient(1)/(2) (setup completes finitely on them at small dt; refusing them is a physics judgement), and the k2-k1 >= 3 wording above is on the same sign-off list.

Every refusal is paired with an accepting baseline in tests/unit/test_l2_msolve.f90; the two-context split means each validator is tested against the type its routine takes.

Defined Subroutines#

mupro_msolve_setup#

Preparation for the msolve solver

call mupro_msolve_setup(context)

Argument	Type(Intent)	Meaning
context	type_mupro_MsolveContext(INOUT)	The msolve setup context

mupro_msolve_solve#

Evolve the Time-Dependent Ginzburg Landau equation semi-implicitly, march forward the order parameter distribution for one time step.

call mupro_msolve_solve(context)

Argument	Type(Intent)	Dimension
context	type_mupro_MsolveSolveContext(INOUT)	The msolve solver context