diff --git a/dgsres/singlextal/simdata.py b/dgsres/singlextal/simdata.py
index 453fc0b..a9c0b61 100644
--- a/dgsres/singlextal/simdata.py
+++ b/dgsres/singlextal/simdata.py
@@ -17,27 +17,30 @@ def __init__(self, parent_dir, dirname_template='E%s_hkl%s'):
     def path(self, hkl, E):
         return os.path.join(self.parent_dir, self.dirname_template % (E, '%s,%s,%s' % tuple(hkl)))
     
-    def loadData(self, hkl, E):
+    def loadData(self, hkl, E, dhkl_ranges=None):
         p = self.path(hkl, E)
-        return self._loadData(p)
+        return self._loadData(p, dhkl_ranges=dhkl_ranges)
     
     def loadPointCloud(self, hkl, E):
         dhs, dks, dls, dEs, probs = self.loadData(hkl, E)
         return PointCloud(dhs, dks, dls, dEs, probs)
     
-    def _loadData(self, outdir1):
+    def _loadData(self, outdir1, dhkl_ranges=None):
+        if dhkl_ranges is None:
+            dhkl_ranges = [ (-2., 2.) ] * 3
         dhkls = np.load('%s/dhkls.npy' % outdir1)
         dEs = np.load('%s/dEs.npy' % outdir1)
         probs = np.load('%s/probs.npy' % outdir1)
         dhs,dks,dls = dhkls.T
         # there might be unreasonable data points with unreasonable weights
-        mask = (dhs> -2.)*(dhs<2.) \
-            * (dks> -2.)*(dks<2.) \
-            * (dls> -2.)*(dls<2.) 
+        (dh_min, dh_max), (dk_min, dk_max), (dl_min, dl_max) = dhkl_ranges
+        mask = (dhs>dh_min)*(dhs<dh_max) \
+            * (dks>dk_min)*(dks<dk_max) \
+            * (dls>dl_min)*(dls<dl_max) 
         return np.array([dhs[mask], dks[mask], dls[mask], dEs[mask], probs[mask]])
     
-    def computeCovMat(self, hkl, E):
-        data = self.loadData(hkl, E)
+    def computeCovMat(self, hkl, E, dhkl_ranges=None):
+        data = self.loadData(hkl, E, dhkl_ranges=dhkl_ranges)
         Data = data[:4]; probs = data[-1]
         return np.cov(Data, aweights=probs)