text: // Copyright 2009 the Sputnik authors.  All rights reserved.
  /**
   * Tangent is a periodic function with period PI
   *
   * @path ch15/15.8/15.8.2/15.8.2.18/S15.8.2.18_A6.js
   * @description Checking if Math.tan(x) equals to Math.tan(x+n*Math.PI) with precision 0.000000000003, where n is an integer from 1 to 100 and x is one of 10 float point values from 0 to Math.PI
   */
  
  // CHECK#1
    prec = 0.00000000003;
  //prec = 0.000000000000001;
  period = Math.PI;
  pernum = 100;
  
  a = -pernum * period + period/2;
  b = pernum * period - period/2;
  snum = 9; 
  step = period/(snum + 2);
  x = new Array();
  for (i = 0; i <= snum; i++)    //// We exlude special points 
  {							   ////           in this cycle.
  	x[i] = a + (i+1)*step;     ////
  }							   ////
  
  
  var curval;
  var curx;
  var j;
  for (i = 0; i < snum; i++)
  {
  	curval = Math.tan(x[i]);
  	curx = x[i] + period;
  	j = 0;
  	while (curx <= b)
  	{
  		curx += period;
  		j++;
  		if (Math.abs(Math.tan(curx) - curval) >= prec)
  		{
  			$FAIL("#1: tan is found out to not be periodic:\n Math.abs(Math.tan(" + x[i] + ") - Math.tan(" + x[i] + " + 2*Math.PI*" + j + ")) >= " + prec + "\n Math.tan(" + x[i] + ") === " + curval + "\n Math.tan(" + curx + ") === " + Math.tan(curx));
  		}
  	}
  }
  
  