A Ruby DSL for operations on Cartesian multidimensional spaces. Features user-defined functions, space conditions, dimensionality-agnostic and dimensionality-aware iterators; named dimensions; dynamic adding/removing dimensions; connection to data sources; tabular output; lazy/eager evaluation; progress bar; import from JSON/YAML/CSV/XLSX; export to Markdown/CSV; DoE with Parametric Behaviour Blueprinting (PBB) to create blueprints of real systems; and interactive HTML heatmaps to model and optimize real systems effortlessly. Code examples: https://github.com/Yuri-Rassokhin/flex-cartesian/tree/main/examples