The article describes an efficient method for handling mesh indexes in multidimensional problems, such as numerical integration of partial differential equations, lattice model simulations, and determining atomic neighbor lists. The method involves creating an extended mesh beyond the periodic unit cell, which allows the stride in memory between equivalent pairs of mesh points to be independent of their position within the cell. This enables the contraction of mesh indexes into a single index, avoiding modulo operations and other implicit index operations. The author demonstrates this method using the calculation of the Laplacian of a function in three dimensions, showing how it can be applied to any linear operator with an arbitrary number of neighbor points. The approach is general and can be used in any space dimensionality, with only one addition and three memory calls required for index operations. The method also allows for further savings by extending the arrays themselves, facilitating parallelization.The article describes an efficient method for handling mesh indexes in multidimensional problems, such as numerical integration of partial differential equations, lattice model simulations, and determining atomic neighbor lists. The method involves creating an extended mesh beyond the periodic unit cell, which allows the stride in memory between equivalent pairs of mesh points to be independent of their position within the cell. This enables the contraction of mesh indexes into a single index, avoiding modulo operations and other implicit index operations. The author demonstrates this method using the calculation of the Laplacian of a function in three dimensions, showing how it can be applied to any linear operator with an arbitrary number of neighbor points. The approach is general and can be used in any space dimensionality, with only one addition and three memory calls required for index operations. The method also allows for further savings by extending the arrays themselves, facilitating parallelization.