Merge branch 'NIFTy_4' into diag_hack

nifty4/minimization/quadratic_energy.py

@@ -31,12 +31,14 @@ class QuadraticEnergy(Energy):
         self._b = b
         if _grad is not None:
             self._grad = _grad
-            Ax = _grad + self._b
+            Ax = _grad if b is None else _grad + b
         else:
             Ax = self._A(self.position)
-            self._grad = Ax - self._b
+            self._grad = Ax if b is None else Ax - b
         self._grad.lock()
-        self._value = 0.5*self.position.vdot(Ax) - b.vdot(self.position)
+        self._value = 0.5*self.position.vdot(Ax)
+        if b is not None:
+            self._value -= b.vdot(self.position)
 
     def at(self, position):
         return QuadraticEnergy(position=position, A=self._A, b=self._b)

nifty4/utilities.py

@@ -84,6 +84,8 @@ def parse_spaces(spaces, nspc):
         spaces = (safe_cast(int, spaces),)
     else:
         spaces = tuple(safe_cast(int, item) for item in spaces)
+    if len(spaces) == 0:
+        return spaces
     tmp = tuple(set(spaces))
     if tmp[0] < 0 or tmp[-1] >= nspc:
         raise ValueError("space index out of range")