diff --git a/test_sampling.py b/test_sampling.py
index 0a67b11..5e85873 100644
--- a/test_sampling.py
+++ b/test_sampling.py
@@ -1,12 +1,18 @@
 import sampling
 import numpy as np
+import pylab
 
 def test_resample():
     x = np.arange(300)
-    s = sampling.Sampler(x)
+    s = sampling.Sampler(x, )
     y = np.array(list(s))
 
-    k = s.interp.width - 1
-    x = x[k:-k-1]
-    err = np.max(np.abs(x - y))
-    assert err < 1e-10
+    w = s.interp.width
+    x = x[w-1:-w]
+    err = x - y
+    assert np.max(np.abs(err)) < 1e-10
+
+def test_coeffs():
+    I = sampling.Interpolator(width=4, resolution=16)
+    err = I.filt[0] - [0,0,0,1,0,0,0,0]
+    assert np.max(np.abs(err)) < 1e-10