var vows = require('vows');
var assert = require('assert');
var suite = vows.describe('jStat.skewness');

require('../env.js');

suite.addBatch({
  'skewness': {
    'topic': function() {
      return jStat;
    },
    'returns accurate skewness value': function(jStat) {
      // from normal distribution in R: > rnorm(12); skewness(set) => -0.03270
      var set =
          [-0.28157961, -0.75577350,  0.61554139,  0.26864022, -0.42703435,
           -0.99927791, -0.07113527, -1.39327183,  0.34871138,  1.17909042,
           -0.22951562,  0.22341714];
      var skew = jStat.skewness(set);

      assert.isTrue(skew > -0.03271);
      assert.isTrue(skew < -0.03269);
    },
    'skewness from instance': function(jStat) {
      var set =
          [-0.28157961, -0.75577350,  0.61554139,  0.26864022, -0.42703435,
           -0.99927791, -0.07113527, -1.39327183,  0.34871138,  1.17909042,
           -0.22951562,  0.22341714];
      var skew = jStat(set).skewness();

      assert.isTrue(skew > -0.03271);
      assert.isTrue(skew < -0.03269);
    }
  }
});

suite.export(module);