 	float reHeight = 0.0; float imHeight = 0.0;
 	float real_part = 0.0; float imag_part = 0.0;
 	float fourier_coefficients = 1.0;
-	vec2 sum = vec2(0);
+	vec2 sum = vec2(0.0, 0.0);
 	
 	// approximation till iteration 30 of fourier coefficient
 	for(int n = lower; n <= upper; n++){

	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);
	
	

	
	
	float stepSize = 1.0;
	sigma_f_pix = ((2.0*dx) / (PI*dimX));
	float comp_sigma = sigma_f_pix;
	sigma_f_pix *= sigma_f_pix;
	sigma_f_pix *= 2.0;
