LayoutCS¶

Usage

use LayoutCS;

class CS¶

This CS layout provides a Compressed Sparse Row (CSR) and Compressed Sparse Column (CSC) implementation for Chapel's sparse domains and arrays.

To declare a CS domain, invoke the CS constructor in a dmapped clause, specifying CSR vs. CSC format with the param compressRows argument, which defaults to true if omitted. For example:

use LayoutCS;
var D = {1..n, 1..m};  // a default-distributed domain
var CSR_Domain: sparse subdomain(D) dmapped CS(compressRows=true); // Default argument
var CSC_Domain : sparse subdomain(D) dmapped CS(compressRows=false);

To declare a CSR or CSC array, use a CSR or CSC domain, respectively. For example:

// assumes the above declarations
var CSR_Array: [CSR_Domain] real;
var CSC_Array: [CSC_Domain] real;

This domain map is a layout, i.e. it maps all indices to the current locale. All elements of a CS-distributed array are stored on the locale where the array variable is declared.