#include<cmath>
using namespace std;

#define NLAYERS_BCAL 10
double BCAL_tdiff(double geometric_mean, int layer)
{
	double tw_par[NLAYERS_BCAL][7] ={
		{11.0672, -12.0531, 3.25046, -0.102684, -0.0674759, 0.00888003, -0.000323306},	// layer 1
		{-110.005, 41.2519, 1.01664, -1.3829, -0.119074, 0.0615181, -0.00427167},	// layer 2
		{521.934, -280.307, 5.35516, 13.9033, 0.733818, -0.900863, 0.0873093},	// layer 3
		{0, 0, 0, 0, 0, 0, 0},	// 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])))));
}