User Guide

Cartesian Grids

Create a starter configuration and generate its grid:

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grid-generator cartesian init
grid-generator cartesian run cartesian.toml

The Cartesian config requires [grid.x]. The [grid.y] and [grid.z] tables are optional:

Each active axis uses the same one-dimensional distribution contract. Supported types are equidistant, geometric, tanh, and segmented.

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[grid]
type = "cartesian"

[grid.x]
type = "equidistant"
start = 0.1
end = 1.0
n_points = 10

[grid.y]
type = "geometric"
start = 0.0
end = 0.05
n_points = 100
first_spacing = 1.0e-6

[output]
filename = "grid.hdf5"
dtype = "f8"

Artifact paths are resolved relative to the configuration file.

Segmented Distributions

A segmented distribution begins with an equidistant region. Quintic regions connect two equidistant regions while matching location, spacing, and zero second derivative at both junctions. A cubic region may terminate the sequence while matching location, spacing, and zero second derivative at its starting junction.

The supported sequence is:

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equidistant (quintic equidistant)* [cubic]

This supports 1-3, 1-5-1, and repeated forms such as 1-5-1-5-1:

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[grid.x]
type = "segmented"
start = 0.0

[[grid.x.segments]]
type = "equidistant"
end = 0.1
spacing = 0.005

[[grid.x.segments]]
type = "quintic"
end = 0.4
n_points = 31

[[grid.x.segments]]
type = "equidistant"
end = 0.6
spacing = 0.01

[[grid.x.segments]]
type = "quintic"
end = 0.8
n_points = 21

[[grid.x.segments]]
type = "equidistant"
end = 1.0
spacing = 0.02

An equidistant segment accepts exactly one of spacing or n_points. Segment point counts include both endpoints. Shared junction points are included once in the assembled distribution.

For spacing-controlled equidistant regions, the region length must be exactly divisible by the requested spacing. Invalid or non-monotone assembled grids are rejected rather than adjusted silently.