How exactly does the -I option work?

[Andi47]

I just tried

ecm -nn -c 100 -I 1 <ecm.txt 5e4 >>out1.txt

The first two curves were done on B1 = 50000 and B1 = 51108 resp., thus indicating a multiplicator of approx. 1.022.

The last two curves were done on B1 = 185663 and B1 = 187373 resp., thus indicating a multiplicator of approx. 1.009.

So how exactly is the increment calculated?

[henryzz]

double
calc_B1_AutoIncrement (double cur_B1, double incB1val, int calcInc)
{
  const double const_adj = 1.33;
  double B1Mod;
  if (!calcInc)
    return cur_B1 + incB1val;  /* incB1val is a constant to add to B1 */

  /* This simple table was "created" based upon the "Optimal B1 table"
     in the README file */
  if (cur_B1 < 2000.)
    B1Mod = 200.;
  else if (cur_B1 < 11000.)  /* 30 curves from B1=2000 to 11000 */
    {
      B1Mod = 300.    * (1. - ((cur_B1 - 2000.) / 9000.));
      B1Mod +=433.334 * (1. - ((11000. - cur_B1) / 9000.));
    }
  else if (cur_B1 < 50000.)  /* 90 curves from B1=11000 to 50000 */
    {
      B1Mod = 433.334 * (1. - ((cur_B1 - 11000.) / 39000.));
      B1Mod +=833.334 * (1. - ((50000. - cur_B1) / 39000.));
    }
  else if (cur_B1 < 250000.)  /* 240 curves from B1=50000 to 250000 */
    {
      B1Mod = 833.334 * (1. - ((cur_B1 - 50000.) / 200000.));
      B1Mod +=1500.   * (1. - ((250000. - cur_B1) / 200000.));
    }
  else if (cur_B1 < 1000000.)  /* 500 curves from B1=250000 to 1e6 */
    {
      B1Mod = 1500.        * (1. - ((cur_B1 - 250000.) / 750000.));
      B1Mod +=1818.18182   * (1. - ((1000000. - cur_B1) / 750000.));
    }
  else if (cur_B1 < 3000000.)  /* 1100 curves from B1=1e6 to 3e6 */
    {
      B1Mod = 1818.18182   * (1. - ((cur_B1 - 1000000.) / 2000000.));
      B1Mod +=2758.621     * (1. - ((3000000. - cur_B1) / 2000000.));
    }
  else if (cur_B1 < 11000000.)  /* 2900 curves from B1=3e6 to 11e6 */
    {
      B1Mod = 2758.621     * (1. - ((cur_B1 - 3000000.) / 8000000.));
      B1Mod +=5818.18182   * (1. - ((11000000. - cur_B1) / 8000000.));
    }
  else if (cur_B1 < 43000000.)  /* 5500 curves from B1=11e6 to 43e6 */
    {
      B1Mod = 5818.18182   * (1. - ((cur_B1 - 11000000.) / 32000000.));
      B1Mod +=7444.44445   * (1. - ((43000000. - cur_B1) / 32000000.));
    }
  else if (cur_B1 < 110000000.)  /* 9000 curves from B1=43e6 to 11e7 */
    {
      B1Mod = 7444.44445   * (1. - ((cur_B1 - 43000000.)  / 67000000.));
      B1Mod +=6818.18182   * (1. - ((110000000. - cur_B1) / 67000000.));
    }
  else if (cur_B1 < 260000000.)  /* 22000 curves from B1=11e7 to 26e7 */
    {
      B1Mod = 6818.18182   * (1. - ((cur_B1 - 110000000.) / 150000000.));
      B1Mod +=11346.1539   * (1. - ((260000000. - cur_B1) / 150000000.));
    }
  else if (cur_B1 < 850000000.)  /* 52000 curves from B1=26e7 to 85e7 */
    {
      B1Mod = 11346.1539   * (1. - ((cur_B1 - 260000000.) / 590000000.));
      B1Mod +=24698.8      * (1. - ((850000000. - cur_B1) / 590000000.));
    }
  else if (cur_B1 < 2900000000.)  /* 83000 curves from B1=85e7 to 29e8 */
    {
      B1Mod = 24698.8      * (1. - ((cur_B1 - 850000000.)  / 2050000000.));
      B1Mod +=50000.0      * (1. - ((2900000000. - cur_B1) / 2050000000.));
    }
  else
    B1Mod = 50000.;

  return floor (cur_B1 + const_adj*(B1Mod*incB1val) + 0.5);
}

this is the code that does it in 6.2.1
edit: whoops copied an extra function

[10metreh]

Originally Posted by Andi47

I just tried

ecm -nn -c 100 -I 1 <ecm.txt 5e4 >>out1.txt

The first two curves were done on B1 = 50000 and B1 = 51108 resp., thus indicating a multiplicator of approx. 1.022.

The last two curves were done on B1 = 185663 and B1 = 187373 resp., thus indicating a multiplicator of approx. 1.009.

So how exactly is the increment calculated?

I got my 1.2 estimate from B1 = 2e3. I didn't check to see if it changed.