Procedures

Allocate all solver work arrays owned by a solver instance.

Update ghost-state vectors from the current solution and BC types.

Fill state%ub with the initial condition selected by cfg%problem_type.

Generic Jiang-Shu WENO reconstruction for odd-width schemes.

AUSM+ FDS scheme (AUSM family).

Banded linear solver using LAPACK dgbsv.

Banded Gaussian elimination without pivoting. Band storage: AB(ku+1+i-j, j) = A(i,j). On exit x = A^{-1} b. The matrix ab_loc is overwritten with LU factors.

Advance the solution by one time step using the BDF2 (Gear) scheme.

Advance the solution by one time step using backward (implicit) Euler.

Convert a NUL-terminated C string into a fixed-length Fortran buffer.

Second-order central reconstruction in physical space.

Advance the solver by at most max_steps iterations.

Copy the primitive solution into caller-owned C buffers.

Allocate the sole supported v1 session and return its opaque handle.

Destroy the active session referenced by handle.

Read a logical configuration field by canonical schema key.

Read an integer configuration field by canonical schema key.

Copy the last surfaced error string into a C buffer.

Return the grid-point count required by solution-copy buffers.

Copy out the current progress snapshot for a session.

Read a scalar real configuration field by canonical schema key.

Read a length-3 real configuration field by canonical schema key.

Read a string or choice-token configuration field by canonical schema key.

Validate config and allocate the runtime owned by handle.

Load a namelist file into the session configuration.

Run the session to completion without intermediate polling.

Return optional numeric bounds for schema entry index.

Copy one allowed string token for a choice-valued schema entry.

Return the number of allowed string choices for schema entry index.

Return the number of schema entries exported through the ABI.

Copy the compiled-in default logical value for schema entry index.

Copy the compiled-in default integer value for schema entry index.

Copy the compiled-in default scalar real value for schema entry index.

Copy the compiled-in default length-3 real vector for schema entry index.

Copy the compiled-in default string or choice token for schema entry index.

Copy the namelist group name for schema entry index.

Copy the short help text for schema entry index.

Copy the canonical key for schema entry index.

Return the cfg_kind_* tag for schema entry index.

Set a logical configuration field by canonical schema key.

Set an integer configuration field by canonical schema key.

Set a scalar real configuration field by canonical schema key.

Set a length-3 real configuration field by canonical schema key.

Set a string or choice-token configuration field by canonical schema key.

Force an immediate checkpoint write for the active runtime.

Write the current solution in the standard text result format.

Evaluate candidate reconstruction polynomials from tabulated coefficients.

Evaluate candidate Jiang-Shu smoothness indicators from quadratic forms.

Compute the right eigenvector matrix K and its inverse K^{-1} of the Euler Jacobian at a given state.

Compute the Euler flux vector F(Q) for a given conserved state.

Evaluate a quadratic smoothness form on the full stencil.

Return the global maximum wave speed max_i(|u_i| + c_i).

Compute the spatial residual R(Q) = -1/dx * (F_{i+1/2} - F_{i-1/2}).

Accumulate the global L2 norm of the residual into state%resid_glob.

Compute Roe-averaged velocity, enthalpy, and sound speed.

Read the compiled-in default integer value for a schema key.

Read the compiled-in default logical value for a schema key.

Read the compiled-in default scalar real value for a schema key.

Read the compiled-in default length-3 real vector for a schema key.

Read the compiled-in default string or choice token for a schema key.

Read one integer-valued field from cfg by schema key.

Read one logical field from cfg by schema key.

Read one scalar real-valued field from cfg by schema key.

Read one fixed-length real-3 field from cfg by schema key.

Read one string or choice token from cfg by schema key.

Return the number of allowed choices for a choice-valued schema entry.

Return the number of published schema entries.

Write one integer-valued field in cfg by schema key.

Write one logical field in cfg by schema key.

Write one scalar real-valued field in cfg by schema key.

Write one fixed-length real-3 field in cfg by schema key.

Write one string or choice token in cfg by schema key.

Copy one 1-based choice-list item into value.

Copy the current solution into primitive-variable arrays.

Nullify procedure pointer components of a solver_state_t instance.

Perform classical ENO3 reconstruction on the supplied stencil.

Populate the schema table on first use.

Advance the solution by one time step using the explicit Euler scheme.

Evaluate the hybrid shock sensor for face iface.

Extract primitive variables (rho, u, p) from a conserved state vector.

Fill a reconstruction stencil from field, applying ghost states at domain boundaries.

Write the final solution to the output file and print the performance table.

Find a schema entry by key and return its 1-based index.

Store the last writable-operation error and mirror it to optional outputs.

Mirror readonly-operation status without mutating the session state.

Copy trimmed Fortran text into a NUL-terminated C buffer.

Copy one allowed string token from a schema entry's choice list.

Copy one schema entry by its 1-based index.

Return the host platform detected by the C portability shim.

Return Q at grid cell idx with ghost-state fallback at boundaries.

Return the preferred runtime-UDF output directory on Windows.

HLL approximate Riemann solver.

HLLC approximate Riemann solver with contact-wave restoration.

Load the initial condition from a data file containing columns: x rho u p.

Compile a user-defined Fortran source file to a shared library at runtime and call its ic_udf subroutine to fill the initial state.

Bind the flux dispatch pointers in @p state to the requested scheme.

Populate a solver_state_t from a config_t.

Bind the reconstruction procedure pointers and stencil metadata in @p state to the requested scheme, then resolve state%use_char_proj.

Bind the procedure pointer @p step to the requested scheme.

Populate ctx and bring the solver to a ready-to-run state.

Store one Jacobian column into band storage AB(diag_row_loc+i-j, j) = J(i,j). Works for both the custom (diag_row_loc = ku+1) and LAPACK (diag_row_loc = kl+ku+1) storage layouts.

Join a directory and leaf name with a platform-appropriate separator.

Lax-Friedrichs flux splitting.

Fused Lax-Friedrichs flux splitting: returns F^+ and F^- in one call.

Koren TVD limiter. Third-order accurate for smooth data; preserves monotonicity near discontinuities.

Monotonized Central (MC) TVD limiter. Good balance between dissipation and resolution; recommended for most shock-capturing applications.

Minmod TVD limiter. Most dissipative of the standard limiters; guaranteed TVD for any CFL within the stability limit.

Superbee TVD limiter. Least dissipative TVD limiter; may over-sharpen contact discontinuities on smooth problems.

van Leer smooth TVD limiter.

Scale a reconstructed face state toward the cell average to ensure density ρ ≥ ε and pressure p ≥ ε (Zhang-Shu 2010).

5th-order linear WENO reconstruction on a 5-point stencil.

7th-order linear WENO reconstruction on a 7-point stencil.

Emit a DEBUG-level message.

Log the effective (post-promotion) configuration at startup. Reads from the authoritative copy ctx % state % cfg, which may differ from the original namelist values when BC promotions have been applied (e.g. smooth_wave → periodic, woodward_colella → reflecting).

Emit an ERROR-level message.

Close the log file and reset file-logging state.

Emit an INFO-level message.

Initialise the logger: set verbosity level and optionally open a log file.

Log one iteration summary line (time, residual, per-iteration and elapsed wall time). The lightweight iter_s and elapsed_s fields are always populated. Called every ctx % print_freq iterations and once unconditionally after the loop.

Print the wall-clock performance table after the run completes. Reports total time, I/O time, and the three hot-path timers (compute_resid, flux precompute, face loop) plus overall throughput. Only called when ctx % state % cfg % do_timing is .true..

Emit a WARN-level message.

Return a left-trimmed, lowercased copy of value. Pure: has no side effects; suitable for use in constant expressions.

Two-argument minmod function. Returns the value with the smaller magnitude if a and b have the same sign, else 0.

Four-argument minmod function. Returns 0 if the arguments do not all share the same sign; otherwise returns the value with the smallest magnitude.

Perform MP5 reconstruction on the supplied stencil.

MUSCL reconstruction with the Koren limiter.

MUSCL reconstruction with the Monotonized Central (MC) limiter.

MUSCL reconstruction with the Minmod limiter.

Core MUSCL reconstruction kernel (component-wise, left-biased stencil).

MUSCL reconstruction with the Superbee limiter.

MUSCL reconstruction with the van Leer smooth limiter.

Lowercase all scheme-selection and option string fields in cfg. Called automatically by validate_config before any comparisons so that namelist values are accepted regardless of the case supplied by the user.

Normalise a user-provided parameter key to lowercase trimmed form.

Flatten a (neq x n_pt) field into a length-neq*n_pt 1-D array. Ordering: (eq=1,cell=1), (eq=2,cell=1), ..., (eq=neq,cell=n_pt).

Pre-compute the boundary split fluxes fl_pos/fl_neg/fr_pos/fr_neg for FVS schemes. No-op when the FDS path is active (state%use_fds = .true.).

Wrap a filesystem path for the shell used by execute_command_line.

Read a checkpoint file and restore solver state.

Read simulation parameters from a namelist file.

Reconstruct a face flux or state with optional characteristic projection.

Release all allocatable arrays owned by a solver instance.

Print the end-of-run performance table once after a completed run.

Tear down the live runtime context while keeping editable config state.

Read the namelist filename from the first command-line argument. Falls back to 'input.nml' when no argument is supplied.

Resolve an opaque C handle to the active Fortran session pointer.

Resolve a scheme name to a specific stepper procedure pointer.

Advance the solution by one time step using the classic RK4 scheme.

Roe approximate Riemann solver with Harten entropy fix.

Execute the main time-marching loop until time_stop is reached.

Advance the main time loop by at most max_steps iterations.

Shared helper for copying one text field from a schema entry into a C buffer.

Fill one slot in the lazily initialised schema table.

Convert namelist primitives (rho_left, u_left, p_left / rho_right, …) to conserved ghost state vectors and optionally pre-compute boundary split fluxes for FVS schemes.

Fan out a success flag and optional message to caller-provided outputs.

Compute banded-storage dimensions for the Newton-step Jacobian.

Advance the runtime by at most max_steps iterations.

Copy the current primitive-variable solution into caller-owned arrays.

Reset a session to its default empty state.

Tear down any live runtime allocations and clear the last error.

Read an integer configuration field by canonical schema key.

Read a logical configuration field by canonical schema key.

Return the current grid-point count expected by solution copy-out buffers.

Copy out a lightweight progress snapshot for polling clients.

Read a scalar real configuration field by canonical schema key.

Read a real-3 configuration field by canonical schema key.

Read a string or choice-token configuration field by canonical schema key.

Validate the current configuration and allocate the runtime context.

Copy the last stored writable-operation error message.

Load configuration from a namelist file into the session.

Run the current session until time_stop is reached.

Set an integer configuration field and invalidate any live runtime.

Set a logical configuration field and invalidate any live runtime.

Set a scalar real configuration field and invalidate any live runtime.

Set a real-3 configuration field and invalidate any live runtime.

Set a string or choice-token configuration field and invalidate any runtime.

Force an immediate checkpoint write using the configured or overridden base name.

Write the current solution in the standard result.dat-style text format.

Advance the solution by one time step using the SSPRK(2,2) scheme.

Advance the solution by one time step using the SSPRK(5,4) scheme.

Steger-Warming flux vector splitting.

Fused Steger-Warming flux splitting: returns F^+ and F^- in one call.

Release all allocations held by ctx and finalise the logger. Must be the last call in the lifecycle; ctx is invalid afterwards.

Perform TENO5 reconstruction on the supplied stencil.

Return elapsed wall time in seconds, including the current running segment.

Return accumulated wall time in seconds.

Print a one-line performance report to stdout.

Reset a timer to the zero state.

Start (or resume) the timer.

Stop the timer and accumulate elapsed counts.

Advance the solution by one time step using the TVD-RK3 scheme.

Add a flattened 1-D correction to a (neq x n_pt) 2-D field in place.

Compute one ghost-state vector and its split fluxes from a boundary cell.

First-order upwind reconstruction.

Second-order upwind reconstruction.

Validate that all namelist parameters are physically and numerically sensible.

van Leer flux vector splitting.

Fused van Leer flux splitting: returns F^+ and F^- in one call.

Perform WENO5-JS reconstruction on the supplied stencil.

Compute the Jiang-Shu smoothness indicators for a 5-point WENO5 stencil.

Compute the three 3rd-order substencil reconstructions for WENO5.

Perform WENO5-Z reconstruction on the supplied stencil.

Perform WENO7-JS reconstruction on the supplied stencil.

Write a single row of primitive variables to io_unit in '(4ES20.12)' format. Shared by finalize_runtime and write_snapshot to avoid duplicating the conserved-to-primitive conversion.

Write a checkpoint file for the current solver state.

Write a live snapshot of the current solution to snapshot_file. The file is overwritten on each call. A header comment records the current iteration and time; subsequent rows are (x, ρ, u, p) via write_cell_row. Open/write failures are logged as warnings rather than fatal errors so that a snapshot glitch does not abort the run. This file path is retained for compatibility with legacy file-watching tooling; new integrations should prefer the polling session/API surface.

Write the current solution to a text file.