Set units correctly on Numpy arrays

wrappers/python/simtk/openmm/app/amberinpcrdfile.py

@@ -32,7 +32,7 @@ __author__ = "Peter Eastman"
 __version__ = "1.0"
 
 from simtk.openmm.app.internal import amber_file_parser
-from simtk.unit import nanometers, picoseconds
+from simtk.unit import Quantity, nanometers, picoseconds
 try:
     import numpy
 except:
@@ -84,7 +84,7 @@ class AmberInpcrdFile(object):
          """
         if asNumpy:
             if self._numpyPositions is None:
-                self._numpyPositions = numpy.array(self.positions.value_in_unit(nanometers))*nanometers
+                self._numpyPositions = Quantity(numpy.array(self.positions.value_in_unit(nanometers)), nanometers)
             return self._numpyPositions
         return self.positions
     
@@ -96,7 +96,7 @@ class AmberInpcrdFile(object):
          """
         if asNumpy:
             if self._numpyVelocities is None:
-                self._numpyVelocities = numpy.array(self.velocities.value_in_unit(nanometers/picoseconds))*nanometers/picoseconds
+                self._numpyVelocities = Quantity(numpy.array(self.velocities.value_in_unit(nanometers/picoseconds)), nanometers/picoseconds)
             return self._numpyVelocities
         return self.velocities
     
@@ -109,9 +109,9 @@ class AmberInpcrdFile(object):
         if asNumpy:
             if self._numpyBoxVectors is None:
                 self._numpyBoxVectors = []
-                self._numpyBoxVectors.append(numpy.array(self.boxVectors[0].value_in_unit(nanometers))*nanometers)
-                self._numpyBoxVectors.append(numpy.array(self.boxVectors[1].value_in_unit(nanometers))*nanometers)
-                self._numpyBoxVectors.append(numpy.array(self.boxVectors[2].value_in_unit(nanometers))*nanometers)
+                self._numpyBoxVectors.append(Quantity(numpy.array(self.boxVectors[0].value_in_unit(nanometers)), nanometers))
+                self._numpyBoxVectors.append(Quantity(numpy.array(self.boxVectors[1].value_in_unit(nanometers)), nanometers))
+                self._numpyBoxVectors.append(Quantity(numpy.array(self.boxVectors[2].value_in_unit(nanometers)), nanometers))
             return self._numpyBoxVectors
         return self.boxVectors