old_contents: /*
   * trend.js
   *
   * Copyright (c) 2015 James G Jenner
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in all
   * copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   * SOFTWARE.
   * 
   * Logic is based on Timothy Banas article on calculating trend line
   * http://classroom.synonym.com/calculate-trendline-2709.html
   * 
   * Some redundancy is kept so that code is comparable to reference material
   */
  
  function calcTrendLine(xSeries, ySeries) {
    if(xSeries.length < ySeries.length) {
      return 0;
    }
  
    var n = ySeries.length;
    var idx;
    var sumPlus = 0;
    var sumSquaredX = 0;
    var sumX = 0;
    var sumY = 0;
  
    for(idx = 0; idx < ySeries.length; idx++) {
      sumPlus += xSeries[idx] * ySeries[idx];
      sumX += xSeries[idx];
      sumY += ySeries[idx];
      sumSquaredX += Math.pow(xSeries[idx], 2);
    }
  
    var a = n * sumPlus;
    var b = sumX * sumY;
    var c = n * sumSquaredX;
    var d = Math.pow(sumX, 2);
    var m = (a - b) / (c - d);
  
    var e = sumY;
    var f = m * sumX;
  
    var bSlope = (e - f) / n;
    var y = m * xSeries.length + bSlope;
  
    return y;
  }
  
new_contents: /*
   * trend.js
   *
   * Copyright (c) 2015 James G Jenner
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in all
   * copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   * SOFTWARE.
   * 
   * Logic is based on Timothy Banas article on calculating trend line
   * http://classroom.synonym.com/calculate-trendline-2709.html
   * 
   * Some redundancy is kept so that code is comparable to reference material
   */
  
  function calcTrendLine(xSeries, ySeries) {
    if(xSeries.length < ySeries.length) {
      return 0;
    }
  
    var n = ySeries.length;
    var idx;
    var sumPlus = 0;
    var sumSquaredX = 0;
    var sumX = 0;
    var sumY = 0;
  
    for(idx = 0; idx < ySeries.length; idx++) {
      sumPlus += xSeries[idx] * ySeries[idx];
      sumX += xSeries[idx];
      sumY += ySeries[idx];
      sumSquaredX += Math.pow(xSeries[idx], 2);
    }
  
    var a = n * sumPlus;
    var b = sumX * sumY;
    var c = n * sumSquaredX;
    var d = Math.pow(sumX, 2);
    var m = (a - b) / (c - d);
  
    var e = sumY;
    var f = m * sumX;
  
    var bSlope = (e - f) / n;
    
    return [[1, _calcYForX(1)], [xSeries.length, _calcYForX(xSeries.length)]];
  
    function _calcYForX(x) {
      return m * x + bSlope;
    }
  }
  
  
subject: Return start and end coords for the trend line