#include<cmath>
using namespace std;

#define NLAYERS_BCAL 10
double BCAL_tdiff(double geometric_mean, int layer)
{
	double tw_par[NLAYERS_BCAL][7] ={
		{-86.4162, 69.3821, -18.3512, 1.07928, 0.308769, -0.0537258, 0.00247848},	// layer 1
		{-500.135, 549.577, -248.069, 58.8461, -7.73426, 0.534002, -0.0151361},	// layer 2
		{-182.66, 137.445, -31.9108, 0.0359604, 1.04127, -0.148554, 0.00653135},	// layer 3
		{-1179.08, 938.408, -218.305, -11.3776, 12.4656, -1.8791, 0.0926652},	// 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])))));
}