Making sure inputs are not modified by MLEM

MLEM.py

@@ -2,14 +2,15 @@ import numpy as np
 
 def MLEM(G, G1, sino, imold, nx, na, nb, R=None, beta=1e-3):
     sino1=G.dot(imold.ravel()).reshape(na,nb)
-    sino /= sino1
+    sino2=sino.copy()
+    sino2 /= sino1
     #G1=np.transpose(G)
     #im1=G1.dot(sino.ravel()).reshape(nx,nx)
     #add regularization
     if R==None:
-        im1=G1.dot(sino.ravel()).reshape(nx,nx)
+        im1=G1.dot(sino2.ravel()).reshape(nx,nx)
     else:
-        v0=G1.dot(sino.ravel())
+        v0=G1.dot(sino2.ravel())
         v1=R.dot(imold.ravel())
         v1=[1+beta*x for x in v1]
         v1=v1.reshape(nx,nx)