 
 
 float thetaR;
-
+float sigma_f_pix;
 
 //error constants
 const float eps_pq = 1.0*pow(10.0, -5.0); 

	if(brdf.y < 1e-5) brdf.y = 0.0;
	if(brdf.z < 1e-5) brdf.z = 0.0;
	
	brdf =  brdf*1000.0*gainF(_k1, _k2)*shadowF;
	brdf.xyz = getBRDF_RGB_T_D65(M_Adobe_XRNew, brdf.xyz);
	
	


			vec2 coord22 = vec2(0.0f);
			
			coord22.x = v * dH/ lambda_iter ;
			coord22.y = u *dH / lambda_iter ;


		// xyz value of color for current wavelength (regarding current wavenumber k).
//		vec2 coords = vec2((k*v/(Omega)) + bias/dimN, (k*u/(Omega)) + bias/dimN);
		
		P = taylorGaussWindow(coord22, k, w);
		
		
		float abs_P_Sq = P.x*P.x + P.y*P.y;
