twogrid

Twogrid is a term used across several domains to denote a two-grid concept. In computing and numerical analysis, it commonly refers to the two-grid method, a simple multigrid technique for solving discretized partial differential equations. The method couples a smooth approximation on a fine grid with a correction computed on a coarser grid, yielding faster convergence than a single-grid iteration. A typical implementation includes a smoothing step, restriction of the residual to the coarse grid, a coarse-grid solve or approximate solve, and prolongation of the correction back to the fine grid. The approach can be combined with various smoothers and grid-transfer operators and is considered a predecessor to more elaborate multigrid schemes such as V-cycle and W-cycle. Its performance depends on problem type, grid geometry, and boundary conditions.

In web design and front-end development, twogrid is sometimes used to describe a two-column responsive layout created with CSS Grid or Flexbox. The layout places primary content and secondary content side by side on wider viewports and typically collapses to a single column on smaller screens. Implementations vary in column widths, alignment, and gutter spacing, but the core idea is to partition the page into two primary regions that adapt to available width.

The term may appear in different software projects or documentation with slightly different meanings. In any context, the emphasis is on a two-part structure rather than a single, unified definition.