Quick Start¶

This guide walks through the bare essentials: installing CEA, running the command-line solver on the supplied sample problems, and calling the Python API.

Prerequisites¶

macOS, Linux, or Windows with a Fortran 2008 compiler (gfortran ≥ 10 or Intel ifort 2021+).
CMake ≥ 3.19 and a build tool (Ninja or Make).
Python ≥ 3.11 if you plan to use the Python binding.

Installation¶

Clone the repository:

git clone https://github.com/nasa/cea
cd cea

Configure and build (the dev preset enables the command-line executable, the libraries, and the Python binding on Linux/macOS):

cmake --preset dev
cmake --build --preset dev

On Windows, prefer an explicit generator instead of the GNU-based preset:

cmake -S . -B build-win -G "Visual Studio 17 2022" -DCMAKE_BUILD_TYPE=Debug -DCEA_ENABLE_BIND_PYTHON=ON
cmake --build build-win --config Debug

Install into a staging directory (defaults to build-dev/install unless you set CMAKE_INSTALL_PREFIX):
```
cmake --install build-dev
```
For the Windows build directory above, install from build-win instead:
```
cmake --install build-win --config Debug
```
After installation, add <install-prefix>/bin to your PATH so the cea executable is discoverable. On Windows (PowerShell):
```
setx PATH "$env:PATH;<install-prefix>\\bin"
```
On macOS/Linux:
```
export PATH="<install-prefix>/bin:$PATH"
```

Running the Sample Problems¶

CEA ships with the NASA RP-1311 example suite in samples/. Once the executable is in your PATH you can run every problem in one shot:

cea samples/rp1311_examples.inp

The solver writes results to samples/rp1311_examples.out; open that file in your editor to inspect the species tables and property profiles. To run a single problem, point the executable at a specific .inp file:

cea samples/example1.inp

Use the -h flag to view additional CLI options for controlling verbosity and output naming.

Quick Python Example¶

The editable install emitted by cmake --build exposes the Python API. From the repository root:

pip install -e .
python - <<'PY'
import numpy as np
from cea import EqSolver, TP, TEMPERATURE, PRESSURE

solver = EqSolver()
solver.set_problem_type(TP)
solver.set_state_property(TEMPERATURE, 3500.0)  # Kelvin
solver.set_state_property(PRESSURE, 1.0e6)      # Pa
solver.set_reactant_fraction("H2", 2.0)
solver.set_reactant_fraction("O2", 1.0)
solution = solver.solve()
print("Equilibrium temperature:", solution.temperature, "K")
print("Major species:", dict(zip(solution.species_names,
                                 np.round(solution.mass_fractions, 3))))
PY

CEA does not perform unit conversions by default; inputs and outputs are in the documented CEA units, and users must convert as needed. Use the conversion factors in cea.units when working across unit systems.

The EqSolver and its siblings RocketSolver, ShockSolver, and DetonationSolver expose the same properties as the Fortran core. See Python Interface for the full API reference.

Reporting Issues¶

If you encounter a bug or surprising result, please open a GitHub issue so we can track it. A solid report includes:

A short summary plus expected vs. actual behavior.
Steps to reproduce, including the command line or script you ran.
Your platform, compiler, and CEA version or Git commit.
Any relevant input/output artifacts. If you find a discrepancy from the legacy code, include the problem.inp file so we can reproduce it.

Next Steps¶

Install – deeper coverage of build options, database generation, and platform-specific notes.
Developer Guide – workflows for contributors and advanced users.
Examples – detailed documentation of every RP-1311 example.