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# 0e 5 compute 5 pointdstencil const bigd omain2 0n1

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Unformatted text preview: 51 FuncCons/operators expecCng scalars can also take... …arrays, causing each element to be passed in sin(A) 2*A ≈ forall a in A do sin(a) forall a in A do 2*a …domains, causing each index to be passed in foo(Inner) ≈ forall i in Inner do foo(i) MulCple arguments promote using zippered iteraCon pow(A, B) ≈ forall (a,b) in zip(A,B) do pow(a,b) 52 Indexing into arrays with domain values results in a sub- array expression (an “array slice”) A[Inner] = B[Inner.translate(0,1)]; = A B 53 Reassigning a domain logically reallocates its arrays ༉  array values are preserved for common indices D = {1..2*m, 1..2*n}; A B 54 Chapel supports several domain types… var OceanSpace = {0..#lat, 0..#long}, AirSpace = OceanSpace by (2,4), IceSpace: sparse subdomain(OceanSpace) = genCaps(); dense strided sparse “steve” “lee” unstructured “sung” associative “david” “jacob” “albert” “brad” var Vertices: domain(opaque) = …, People: domain(string) = …; 55 All domain types can be used to declare arrays… var Ocean: [OceanSpace] real, Air: [AirSpace] real, IceCaps[IceSpace] real; var Weight: [Vertices] real, “steve” “lee” “sung” “david” “jacob” “albert” “brad” Age: [People] int; 56 …to iterate over index sets… forall ij in AirSpace do Ocean[ij] += IceCaps[ij]; “steve” “lee” “sung” “david” “jacob” “albert” “brad” forall v in Vertices do Weight[v] = numEdges[v]; forall p in People do Age[p] += 1; 57 …to slice arrays… Ocean[AirSpace] += IceCaps[AirSpace]; “steve” “lee” “sung” “david” “jacob” “albert” “brad” …Vertices[Interior]… …People[Interns]… 58 …and to reallocate arrays AirSpace = OceanSpace by (2,2); IceSpace += genEquator(); newnode = Vertices.create(); “steve” “lee” “sung” “david” “jacob” “albert” “brad” “vass” People += “vass”; 59 var Presidents: domain(string) = {“George”, “John”, “Thomas”, “James”, “Andrew”, “Martin”}; Presidents += “William”; var Age: [Presidents] int, Birthday: [Presidents] string; Birthday[“George”] = “Feb 22”; forall president in President do if Birthday[president] == today then Age[president] += 1; George John Thomas James Andrew Mar3n William Presidents Feb 22 Oct 30 Apr 13 Mar 16 Mar 15 Dec 5 Feb 9 277 274 266 251 242 227 236 Birthday Age 60 Jacobi Iteration in Pictures n A: n 1.0 Σ ÷4 repeat until max change < ε Jacobi Iteration in Chapel config const n = 6, epsilon = 1.0e-5; const BigD: domain(2) = {0..n+1, 0..n+1}, D: subdomain(BigD) = {1..n, 1..n}, LastRow: subdomain(BigD) = D.exterior(1,0); var A, Temp : [BigD] real; A[LastRow] = 1.0; do { [(i,j) in D] Temp[i,j] = (A[i-1,j] + A[i+1,j] + A[i,j-1] + A[i,j+1]) / 4; const delta = max reduce abs(A[D] - Temp[D]); A[D] = Temp[D...
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