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• #ADDING A CHUNK OF RCODE FULL#

When running in parallel mode, each of the chunks identified for the Here's an example of how this looks for chunk 3 in the figure above: (stored in the fields_chunk and dft_chunk structures). For eachĬhunk, these are represented by ivecs named is and ie Of the lower-left and upper-right grid points in the chunk. Of the interval for each coordinate, or equivalently the coordinates The extents of the chunk it thus suffices to specify the endpoints Chunk StatisticsĪs noted above, each chunk is a contiguous region of space definedīy a Cartesian product of intervals for each coordinate to specify

In particular, consecutive chunks are not necessarily adjacent. Note that the chunks are not of uniform sizes and that their ordering is somewhat arbitrary.

The width of the 8 chunks around the perimeter is set by the PML thickness. In a single-processor run, libmeep subdivides this geometry On all sides, discretized with 5 points per unit length Of dimensions, with PML layers of thickness 1 Our running example throughout this page will be a 2d geometry,

#ADDING A CHUNK OF RCODE FULL#

Only tabulated on a subset of the full grid, the grid volumeĬovered by a dft_chunk may be only a subset of the volumeĬovered by its parent fields_chunk, and not all fields_chunks Whichever one stores the time-domain fields at the grid pointsĬovered by the DFT chunk) however, because DFT fields are typically Is associated with a single instance of fields_chunk (namely, Of the time-domain field components at grid points in the chunk).įrequency-domain (DFT) field components are handled by a separateĭata structure called dft_chunk. Points in the chunk) and fields_chunk (storing the actual values Geometry of the chunk and the material properties at grid The data structures structure_chunk (storing data on the This is discussed in moreįor each chunk in a geometry, libmeep creates instances of That take care of many of the above hassles. When implementing loops over grid points, libmeep providesĪ convenient routine called loop_in_chunks and a set of macros To shield developers from the need to grapple with these complications Necessarily involves a certain average over neighboring grid points. Way, obtaining a full set of field-component values at any one grid point Only E-field sites, or only H-field sites, or both? Either "looping over grid points" can mean multiple things - are we visiting Similarly, for Bloch-periodic geometries, only grid points in the unit cellĪre stored, but we may want the fields at a point lying outside the unit cell,Īgain requiring a bit of a shell game to process correctly.īecause of the staggered nature of the Yee grid, Portion of the full grid is actually stored in memory, and obtaining valuesįor field components at a point that isn't stored requires a tricky

It is complicated by several factors, including the following:įor calculations that exploit symmetry, only a In principle, this involves nested for loops in practice, Yee grid, generally performing some operation involving the fieldĬomponents and material parameters at each point. Many internal operations in Meep consist of looping over points in the In parallel calculations, each chunk is assigned, in its entirety, to precisely one process - that is, no chunk exists partly on one processor and partly on another. Each chunk is a contiguous region of space - a line, rectangle, or parallelepiped for 1d/2d/3d Cartesian geometries, or an annular section in a cylindrical geometry-whose sizes are automatically determined by libmeep. Is There a Version of loop_in_chunks for dft_chunks?Īs described in Computer Physics Communications, Vol.Coordinates and Field Components of Symmetry-Reduced Points.Tutorial/Multilevel Atomic Susceptibility.Tutorial/Resonant Modes and Transmission in a Waveguide Cavity.Synchronizing the Magnetic and Electric Fields.