diff --git a/qpms/qpms_p.py b/qpms/qpms_p.py
index 6d3f937..f3d277f 100644
--- a/qpms/qpms_p.py
+++ b/qpms/qpms_p.py
@@ -740,3 +740,36 @@ def G0_sum_1_slow(source_cart, dest_cart, k, nmax):
     return G_Mie_scat_precalc_cart(source_cart, dest_cart, RH, RV, a=0.001, nmax=nmax, k_i=1, k_e=k, μ_i=1, μ_e=1, J_ext=1, J_scat=3)
 
 
+def loadWfile(fileName, lMax = None):
+    '''
+    Load the translation operator lattice sums generated by hexlattice_ewald.c
+    '''
+    nparticles = 2 # TODO generalize
+    um = 1e-6 # micrometer in SI units
+    data = np.loadtxt(fileName)
+    nsamples = data.shape[0]
+    Wdata = data[:,5:]
+    if (lMax is None):
+        nelem = int((Wdata.shape[1]/nparticles**2)**.5/2)
+        lMax = nelem2lMax(nelem)
+    else:
+        nelem = lMax2nelem(lMax)
+    Ws = Wdata[:,::2] + 1j*Wdata[:,1::2]
+    # indices: destparticle, srcparticle, wavetype, desty, srcy
+    Ws.shape = (nsamples, nparticles, nparticles, 2, nelem, nelem) 
+    # maybe TODO copy the following so the original data gets freed to save memory
+    freqs_weirdunits = data[:,0]
+    k0s = data[:,2]
+    ks = data[:,3:4]
+    freqs = freqs_weirdunits * c / um
+    return {
+            'freqs' : freqs,
+            'ks' : ks,
+            'k0s' : k0s,
+            'Ws' : Ws,
+            'freqs_weirdunits' : freqs_weirdunits,
+            }
+
+
+
+