This is the direct translation of the Uber H3 API, with some changes, since it's C# instead of C. No pointers or pointer addresses, so functions that use them in the original tend to have an out parameter where the results will be placed.
Additionally, something I discovered is that Microsoft basically took a shortcut in their trigonometric functions that are still accurate to many decimal points, but not enough. As such, this required a retool to use decimal data types and an external library to maintain that accuracy for trig operations.
All your non-integer values, as such, will be in the decimal data type. I'd recommend performing your H3 operations sequentially, then if you have need of the final result in another type, do your cast then. Interim casts then recast back to decimal are not guaranteed to maintain correctness.
Indexing functions - These functions are used for finding the H3 index containing coordinates, and for finding the center and boundary of H3 indexes.
Index Inspection Functions - These functions provide metadata about an H3 index, such as its resolution or base cell, and provide utilities for converting into and out of the 64-bit representation of an H3 index.
Grid Traversal Functions - Grid traversal allows finding cells in the vicinity of an origin cell, and determining how to traverse the grid from one cell to another.
Hierarchal Grid Functions - These functions permit moving between resolutions in the H3 grid system. The functions produce parent (coarser) or children (finer) cells.
Region Functions - These functions convert H3 indexes to and from polygonal areas.
Unidirectional Edge Functions - Unidirectional edges allow encoding the directed edge from one cell to a neighboring cell.
Miscellaneous H3 Functions - These functions include descriptions of the H3 grid system.