#include<cmath>
using namespace std;

#define NLAYERS_BCAL 10
double BCAL_tdiff(double geometric_mean, int layer)
{
	double tw_par[NLAYERS_BCAL][7] ={
		{-42.091, 22.6633, -1.16054, -0.784213, -0.00299602, 0.0330077, -0.00290217},	// layer 1
		{-96.5425, 63.857, -13.0189, 0.152476, 0.266558, -0.0321849, 0.00115725},	// layer 2
		{53.315, -41.8008, 11.2752, -0.777142, -0.163096, 0.0306444, -0.00144429},	// layer 3
		{2891.89, -3179.12, 1432.47, -338.968, 44.4712, -3.06978, 0.0871732},	// 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])))));
}