#include<cmath>
using namespace std;

#define NLAYERS_BCAL 10
double BCAL_tdiff(double geometric_mean, int layer)
{
	double tw_par[NLAYERS_BCAL][7] ={
		{62.7149, -44.9404, 10.5769, -0.490791, -0.16016, 0.0238154, -0.000965775},	// layer 1
		{-31.4525, 28.022, -7.92631, 0.504649, 0.134489, -0.023983, 0.00111193},	// layer 2
		{-256.247, 205.174, -49.4403, -0.472875, 1.92289, -0.279913, 0.0126826},	// layer 3
		{-637.12, 466.139, -95.1555, -7.23285, 5.22544, -0.683632, 0.0294245},	// layer 4
		{-132.17, 57.7749, 0.847114, -2.34057, -0.194183, 0.122118, -0.00925161},	// 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])))));
}