#include<cmath>
using namespace std;

#define NLAYERS_BCAL 10
double BCAL_tdiff(double geometric_mean, int layer)
{
	double tw_par[NLAYERS_BCAL][7] ={
		{252.241, -213.556, 58.3394, -1.99201, -1.77564, 0.306726, -0.0155324},	// layer 1
		{-469.968, 362.054, -90.6483, 2.82165, 2.38112, -0.384162, 0.0182787},	// layer 2
		{-155.953, 129.828, -34.644, 0.980211, 1.08411, -0.181971, 0.00905403},	// layer 3
		{-199.853, 160.144, -39.8656, 0.137643, 1.47673, -0.228978, 0.0109547},	// layer 4
		{809.346, -414.548, 6.59404, 19.3379, 0.965198, -1.15876, 0.108721},	// layer 5
		{-707.693, 544.759, -126.689, -2.93755, 5.57686, -0.82343, 0.0387892},	// layer 6
		{145.691, -72.589, -0.147108, 3.57523, 0.263875, -0.228643, 0.0207137},	// 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])))));
}