nomogram

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A repository of scientific formulas: alternative notations across authors and conventions, parameter units (including empirical ones), validity domains, LaTeX rendering and symbolic computation.

Pure Python, built on SymPy, numpy and pint; it works on an offline workstation (no online engine).

Early stage project (alpha).

Installation

pip install nomogram          # core
pip install "nomogram[viz]"   # with plots (matplotlib)

Installation from source

git clone https://github.com/miki4iaml/nomogram.git
cd nomogram
uv sync

Python 3.12 or later. Plots need the viz extra (matplotlib): uv sync --extra viz.

Example

Every saturation vapour pressure formulation of the catalog against the IAPWS reference; curves stop where a formulation leaves its stated validity domain (script):

import numpy as np
from nomogram.catalog import catalog
from nomogram.comparison import compare
from nomogram.plot import plot_deviations  # extra viz
from nomogram.units import Q_

formulations = catalog().formulations_of("SaturationVapourPressureOverWater")
reference = catalog().formulations["iapws_sr1_86"]
temperatures = Q_(np.linspace(-60, 110, 341), "degC")

table = compare(formulations, reference, {"ThermodynamicTemperature": temperatures})
plot_deviations(table)

Usage

The table holds the values and the relative deviations, by formulation; values outside a formulation's validity domain are NaN unless asked otherwise (outside="ignore"). Formulations also chain, for instance the absolute humidity from any saturation vapour pressure formulation:

from nomogram.comparison import compose

ha = compose(catalog().formulations["mass_concentration_ideal_gas"], {"e_s": reference})
ha.evaluate(RH=Q_(100, "percent"), T=Q_(20, "degC")).to("g/m^3")  # 17.29

Each formulation keeps its units, validity domain, temperature scale and references. The vocabulary is mapped in docs/rosetta.md; How nomogram earns trust explains what is checked and how.

Contributing

References to integrate, information or corrections about catalog entries, new formulas and code are all welcome: see the ways to contribute and the catalog guide.

License

BSD-3-Clause.