#include<cmath>
using namespace std;

#define NLAYERS_BCAL 10
double BCAL_tdiff(double geometric_mean, int layer)
{
	double tw_par[NLAYERS_BCAL][7] ={
		{-523.661, 580.584, -262.655, 62.1095, -8.10291, 0.553576, -0.0154922},	// layer 1
		{-2007.92, 2194.7, -990.803, 236.362, -31.4115, 2.20418, -0.0637876},	// layer 2
		{-27.2736, 17.488, -0.492699, -0.912715, -0.0475612, 0.0550325, -0.00487664},	// layer 3
		{-9699.07, 8543.23, -2235.52, -94.4309, 142.392, -23.7997, 1.28335},	// layer 4
		{0, 0, 0, 0, 0, 0, 0},	// layer 5
		{0, 0, 0, 0, 0, 0, 0},	// layer 6
		{0, 0, 0, 0, 0, 0, 0},	// layer 7
		{0, 0, 0, 0, 0, 0, 0},	// layer 8
		{0, 0, 0, 0, 0, 0, 0},	// layer 9
		{0, 0, 0, 0, 0, 0, 0}	// layer 10
		};

	layer = layer<1 ? 1:layer>NLAYERS_BCAL ? NLAYERS_BCAL:layer;
	double *p = tw_par[layer-1];
	double x = log(geometric_mean);
	return p[0]+x*(p[1]+x*(p[2]+x*(p[3]+x*(p[4]+x*(p[5]+x*p[6])))));
}