# GeoFLAC

GeoFLAC is a numerical solver for geodynamic modeling, simulating long-term tectonic and lithospheric deformation using a fast Lagrangian analysis of continua (FLAC) method.

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## 🚀 Quick-Start Guide

To get up and running quickly—including compiling the solver, running the standard subduction case, and visualizing the numerical results—please refer to the step-by-step guide:

👉 **[Quick-Start Guide](doc/quickstart.md)**

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## 📖 Solver Documentation

The `doc/` directory contains comprehensive manuals and reference materials for configuring and troubleshooting your simulations:

* **[Quick-Start Guide](doc/quickstart.md)**: Steps to build and run your first model.
* **[Input Parameter Reference](doc/input_description.md)**: Detailed descriptions of all parameters inside the `.inp` configuration file.
* **[Troubleshooting Guide](doc/troubleshooting.md)**: A complete reference of numeric/textual `STOP` exit codes, common runtime errors, stability limits, and their resolutions.

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## 🛠️ Advanced Compilation Options

While the Quick-Start Guide covers standard compilation, the GeoFLAC Makefile supports several advanced compilation flags when compiling in the `src/` directory:

```bash
# General usage:
make F90=<f90 compiler> [FLAGS]
```

### Supported Compilers
* `gfortran` — GNU compiler (default, v4.2 or later required for OpenMP support).
* `ifort` — Intel compiler.
* `pgf90` — PGI compiler (required for compiling GPU acceleration with OpenACC).
* `f90` — Sun Studio compiler.

### Build Flags
* `debug=1` — Build a debugging binary (enables bounds-checking and detects runtime coding errors).
* `omp=0` — Disable OpenMP (multi-threaded CPU parallelization).
* `acc=1` — Enable OpenACC (GPU acceleration).
* `coverage=1` — Perform code coverage analysis (only supported by `gfortran`).
* `gprof=1` — Enable profiling with `gprof`.

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*Original author: Eh Tan (June 2020)*