#include<math.h>
/*-----------------------------------------------------------*/
double ET_PreDesign_Sensitivity(double f) 
/*-----------------------------------------------------------*/
{ 
  double S0, Sn, x, x2, x3, x4, x5, x6;
  double a0, b0, b1, b2, b3, b4, b5, b6, c1, c2, c3, c4, p1, p2;

  x = f/200.;
  x2 = x * x;
  x3 = x2 * x;
  x4 = x2 * x2;
  x5 = x3 * x2;
  x6 = x3 * x3;
   
  p1 = -4.05049;
  p2 = -0.687263;

  a0 = 185.623;
  b0 = 232.565;
  b1 = 31.1777;
  b2 = -64.7178;
  b3 = 52.242;
  b4 = -42.1643;
  b5 = 10.1708;
  b6 = 11.5317;

  c1 = 13.5793;
  c2 = -36.4586;
  c3 = 18.5625;
  c4 = 27.4297;

  S0 = 1.449936e-52;

  Sn = pow(x,p1) + a0*pow(x,p2) + b0 * ( 1. + b1*x + b2*x2 + b3*x3 + 
       b4*x4 + b5*x5 + b6*x6 )/(1. + c1*x + c2*x2 + c3*x3 + c4*x4);
  return(S0 * Sn);

}