//The format of 'size' is two integers separated with a '*'. //The first integer is the domain size squired and the second integer is //the number of iterations. config const size = "100*10";//Default, 100 by 100 domain and 10 iterations //Stop condition in amount of change (ignored when 'iterations' are non-zero). config const epsilon = 1.0e-10; //Parse the --size argument into 'n' and 'iterations' use Regexp; const arg = size.matches(compile("(\\d+)*(\\d+)")); const arg_n = arg[1][1]; const arg_i = arg[2][1]; const n = size[arg_n.offset+1..arg_n.offset+arg_n.length] : int; const iterations = size[arg_i.offset+1..arg_i.offset+arg_i.length]: int; //Initiate a Timer object use Time; var timer : Timer; //Now, let's implement the heat equation! //We will use the Block distribution use BlockDist; //A n+2 by n+2 domain. const Grid = {0..n+1, 0..n+1} dmapped Block({1..n, 1..n}); //A n by n domain that represents the interior of 'Grid' const Interior = {1..n, 1..n} dmapped Block({1..n, 1..n}); var A, T : [Grid] real;//Zero initialized as default A[..,0] = -273.15; //Left column A[..,n+1] = -273.15; //Right column A[n+1,..] = -273.15; //Bottom row A[0,..] = 40.0; //Top row timer.start(); var iter_count = 0; do{ //Since all iterations are independent, we can use 'forall', which allows //the Chapel runtime system to calculate the iterations in parallel forall (i,j) in Interior do//Iterate over all non-border cells { //Assign each cell in 'T' the mean of its neighboring cells in 'A' T[i,j] = (A[i,j] + A[i-1,j] + A[i+1,j] + A[i,j-1] + A[i,j+1]) / 5; } //Delta is the total amount of change done in this iteration const delta = + reduce abs(A[Interior] - T[Interior]); //Copy back the non-border cells A[Interior] = T[Interior]; //if 'iterations' is non-zero we stop after a fixed number of iterations //otherwise we stop when the calculation has converged, i.e. 'delta' is smaller than 'epsilon'. var stop = false; if(iterations > 0) { if iter_count >= iterations then stop = true; } else { if delta < epsilon then stop = true; } } while (!stop); timer.stop(); writeln("Heat Equation (multiple machines) - n: ",n, ", iterations: ", iterations, ", elapsed: ", timer.elapsed(), " seconds");