#version 2.0

/* global-sum-test.diderot
 *
 * This program tests the use of global reductions in a program.
 *
 * This code is part of the Diderot Project (http://diderot-language.cs.uchicago.edu)
 *
 * COPYRIGHT (c) 2016 The University of Chicago
 * All rights reserved.
 */

const int N = 10;
real stdev = ∞;

strand S (int i) {
  output real e = i;

  update {
    stabilize;
  }

}

create_collection { S(i) | i in 1..N }

update {
//  real var = variance{P.energy | P in Particle.all};
  real avg = mean{ strnd.e | strnd in S.all};
  real var = sum{(avg - strnd.e)^2 | strnd in S.all};
  stdev = sqrt(var);
  print("update: stdev = ", stdev, "\n");
}