diff --git a/rainbow.py b/rainbow.py
index fa076a2..9498566 100644
--- a/rainbow.py
+++ b/rainbow.py
@@ -69,14 +69,43 @@ def trace(disk:Disk, stack:list, max_ray:int):
 					result.append([np.arccos(direction[1]), ray.intensity*direction[1]])
 	print("ray trace finish, total ray count:",ray_count)
 
-init()
-# stack.append(Ray([0.8, 2*r], [0,-1], 1))
-trace(disk, stack, max_ray)
+def water_density(t):
+	data_t = np.linspace(0,101,102)
+	data_rho = np.array([999.79,999.84,999.88,999.92,999.97,999.92,999.88,999.84,999.79,999.72,999.65,999.55,999.44,999.32,999.19,999.05,998.90,998.74,998.56,998.36,998.16,997.96,997.74,997.50,997.25,996.99,996.74,996.48,996.20,995.90,995.59,995.29,995.97,994.65,994.33,994.98,993.64,993.28,992.93,992.55,992.17,991.78,991.39,990.99,990.57,990.16,989.75,989.33,988.90,988.45,988.04,987.55,987.06,986.58,986.19,985.70,985.22,984.73,984.67,983.18,983.13,982.70,982.22,981.64,981.06,980.48,979.91,979.33,978.85,978.28,977.70,977.13,976.56,975.99,975.41,974.84,974.27,973.70,973.14,972.47,971.81,971.25,970.59,969.93,969.27,968.61,967.96,967.30,966.65,965.99,965.34,964.69,964.04,963.39,962.64,961.90,961.26,960.52,959.78,959.04,958.40,957.67])
+	return np.interp(t, data_t, data_rho)
 
-with open("result.csv", 'w', newline='') as f:
-    writer = csv.writer(f)
-    writer.writerows(result)
+def water_refraction_index(t, wavelength):
+	rhobar = 0.999974950 * (1 - (t - 3.983035)*(t - 3.983035)*(t + 301.797)/(522528.9*(t+69.34881)))
+	print(rhobar)
+	a0 = 0.244257733
+	a1 = 0.00974634476
+	a2 = -0.00373234996
+	a3 = 0.000268678472
+	a4 = 0.0015892057
+	a5 = 0.00245934259
+	a6 = 0.90070492
+	a7 = -0.0166626219
+	Tstar = 273.15
+	Tbar = 1 + t/Tstar
+	lambdastar = 589
+	lambdabar = wavelength/lambdastar
+	lambda_IR = 5.432937
+	lambda_UV = 0.229202
+	C = a0 + a1*rhobar + a2*Tbar + a3*lambdabar*lambdabar*Tbar + a4/(lambdabar*lambdabar) + a5/((lambdabar+lambda_UV)*(lambdabar-lambda_UV)) + a6/((lambdabar + lambda_IR)*(lambdabar - lambda_IR)) + a7*rhobar*rhobar
+	C *= rhobar
+	n = np.sqrt((2*C+1)/(1-C))
+	return n
 
-with open("points.csv", 'w', newline='') as f:
-    writer = csv.writer(f)
-    writer.writerows(points)
+# init()
+# # stack.append(Ray([0.8, 2*r], [0,-1], 1))
+# trace(disk, stack, max_ray)
+
+# with open("result.csv", 'w', newline='') as f:
+#     writer = csv.writer(f)
+#     writer.writerows(result)
+
+# with open("points.csv", 'w', newline='') as f:
+#     writer = csv.writer(f)
+#     writer.writerows(points)
+
+print(water_refraction_index(10, 226.5))