Add Chapel parallel programming language.

Includes several example programs from source distribution.
2026-02-12 03:09:31 +00:00 · 2014-07-02 14:51:15 -07:00
parent e274196441
commit a6ccce7b76
7 changed files with 3097 additions and 3 deletions
--- a/samples/Chapel/nbody.chpl
+++ b/samples/Chapel/nbody.chpl
@@ -0,0 +1,147 @@
+/* The Computer Language Benchmarks Game
+   http://benchmarksgame.alioth.debian.org/
+
+   contributed by Albert Sidelnik
+   modified by Brad Chamberlain
+*/
+
+
+//
+// The number of timesteps to simulate; may be set via the command-line
+//
+config const n = 10000;
+
+//
+// Constants representing pi, the solar mass, and the number of days per year
+//
+const pi = 3.141592653589793,
+      solarMass = 4 * pi**2,
+      daysPerYear = 365.24;
+
+//
+// a record representing one of the bodies in the solar system
+//
+record body {
+  var pos: 3*real;
+  var v: 3*real;
+  var mass: real;  // does not change after it is set up
+}
+
+//
+// the array of bodies that we'll be simulating
+//
+var bodies = [/* sun */
+              new body(mass = solarMass),
+
+              /* jupiter */
+              new body(pos = ( 4.84143144246472090e+00,
+                              -1.16032004402742839e+00,
+                              -1.03622044471123109e-01),
+                         v = ( 1.66007664274403694e-03 * daysPerYear,
+                               7.69901118419740425e-03 * daysPerYear,
+                              -6.90460016972063023e-05 * daysPerYear),
+                      mass =   9.54791938424326609e-04 * solarMass),
+  
+              /* saturn */
+              new body(pos = ( 8.34336671824457987e+00,
+                               4.12479856412430479e+00,
+                              -4.03523417114321381e-01),
+                         v = (-2.76742510726862411e-03 * daysPerYear,
+                               4.99852801234917238e-03 * daysPerYear,
+                               2.30417297573763929e-05 * daysPerYear),
+                      mass =   2.85885980666130812e-04 * solarMass),
+
+              /* uranus */
+              new body(pos = ( 1.28943695621391310e+01,
+                              -1.51111514016986312e+01,
+                              -2.23307578892655734e-01),
+                         v = ( 2.96460137564761618e-03 * daysPerYear,
+                               2.37847173959480950e-03 * daysPerYear,
+                              -2.96589568540237556e-05 * daysPerYear),
+                      mass =   4.36624404335156298e-05 * solarMass),
+
+              /* neptune */
+              new body(pos = ( 1.53796971148509165e+01,
+                              -2.59193146099879641e+01,
+                               1.79258772950371181e-01),
+                         v = ( 2.68067772490389322e-03 * daysPerYear,
+                               1.62824170038242295e-03 * daysPerYear,
+                              -9.51592254519715870e-05 * daysPerYear),
+                      mass =   5.15138902046611451e-05 * solarMass)
+              ];
+
+//
+// the number of bodies to be simulated
+//
+const numbodies = bodies.numElements;
+
+//
+// The computation involves initializing the sun's velocity,
+// writing the initial energy, advancing the system through 'n'
+// timesteps, and writing the final energy.
+//
+proc main() {
+  initSun();
+
+  writef("%.9r\n", energy());
+  for 1..n do
+    advance(0.01);
+  writef("%.9r\n", energy());
+}
+
+//
+// compute the sun's initial velocity
+//
+proc initSun() {
+  const p = + reduce (for b in bodies do (b.v * b.mass));
+  bodies[1].v = -p / solarMass;
+}
+
+//
+// advance the positions and velocities of all the bodies
+//
+proc advance(dt) {
+  for i in 1..numbodies {
+    for j in i+1..numbodies {
+      updateVelocities(bodies[i], bodies[j]);
+      
+      inline proc updateVelocities(ref b1, ref b2) {
+        const dpos = b1.pos - b2.pos,
+               mag = dt / sqrt(sumOfSquares(dpos))**3;
+        
+        b1.v -= dpos * b2.mass * mag;
+        b2.v += dpos * b1.mass * mag;
+      }
+    }
+  }
+  
+  for b in bodies do
+    b.pos += dt * b.v;
+}
+
+//
+// compute the energy of the bodies
+//
+proc energy() {
+  var e = 0.0;
+  
+  for i in 1..numbodies {
+    const b1 = bodies[i];
+    
+    e += 0.5 * b1.mass * sumOfSquares(b1.v);
+    
+    for j in i+1..numbodies {
+      const b2 = bodies[j];
+      
+      e -= (b1.mass * b2.mass) / sqrt(sumOfSquares(b1.pos - b2.pos));
+    }
+  }
+  
+  return e;
+}
+
+//
+// a helper routine to compute the sum of squares of a 3-tuple's components
+//
+inline proc sumOfSquares(x)
+  return x(1)**2 + x(2)**2 + x(3)**2;