#include<cmath>
using namespace std;

#define NLAYERS_BCAL 10
double BCAL_tdiff(double geometric_mean, int layer)
{
	double tw_par[NLAYERS_BCAL][7] ={
		{-837.336, 936.829, -429.221, 103.03, -13.6685, 0.950893, -0.0271269},	// layer 1
		{-4.3606, -7.01957, 3.65522, -0.294543, -0.0844843, 0.0157111, -0.00072943},	// layer 2
		{-365.355, 288.5, -67.8631, -1.82996, 3.08784, -0.451461, 0.0210304},	// layer 3
		{243.577, -151.754, 7.53071, 7.98019, 0.178117, -0.535643, 0.0571827},	// 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])))));
}