yt : [INFO     ] 2018-03-07 19:08:19,040 Parameters: current_time              = 75.816550478681
yt : [INFO     ] 2018-03-07 19:08:19,040 Parameters: domain_dimensions         = [32 32 32]
yt : [INFO     ] 2018-03-07 19:08:19,041 Parameters: domain_left_edge          = [0. 0. 0.]
yt : [INFO     ] 2018-03-07 19:08:19,041 Parameters: domain_right_edge         = [1. 1. 1.]
yt : [INFO     ] 2018-03-07 19:08:19,041 Parameters: cosmological_simulation   = 1
yt : [INFO     ] 2018-03-07 19:08:19,041 Parameters: current_redshift          = 1.440047878975
yt : [INFO     ] 2018-03-07 19:08:19,041 Parameters: omega_lambda              = 0.727
yt : [INFO     ] 2018-03-07 19:08:19,041 Parameters: omega_matter              = 0.273
yt : [INFO     ] 2018-03-07 19:08:19,041 Parameters: hubble_constant           = 0.702
Parsing Hierarchy : 100%|████████████████████████████████████████████████████████████████████████████████████████████████████████████| 86/86 [00:00<00:00, 29134.17it/s]
yt : [INFO     ] 2018-03-07 19:08:19,054 Gathering a field list (this may take a moment.)
yt : [INFO     ] 2018-03-07 19:08:20,111 xlim = 0.000000 1.000000
yt : [INFO     ] 2018-03-07 19:08:20,112 ylim = 0.000000 1.000000
yt : [INFO     ] 2018-03-07 19:08:20,112 xlim = 0.000000 1.000000
yt : [INFO     ] 2018-03-07 19:08:20,112 ylim = 0.000000 1.000000
yt : [INFO     ] 2018-03-07 19:08:20,117 Making a fixed resolution buffer of (('gas', 'radial_velocity')) 800 by 800
yt : [WARNING  ] 2018-03-07 19:08:20,148 Plot image for field ('gas', 'radial_velocity') has both positive and negative values. Min = -26835038.250923, Max = 43379290.483707.
yt : [WARNING  ] 2018-03-07 19:08:20,148 Switching to symlog colorbar scaling unless linear scaling is specified later
yt : [INFO     ] 2018-03-07 19:08:20,790 Saving plot DD0015_Slice_z_radial_velocity.png
Traceback (most recent call last):
  File "PP.py", line 9, in <module>
    p.save()
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/yt/visualization/plot_container.py", line 96, in newfunc
    rv = f(*args, **kwargs)
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/yt/visualization/plot_container.py", line 509, in save
    names.append(v.save(n, mpl_kwargs))
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/yt/visualization/base_plot_types.py", line 157, in save
    canvas.print_figure(name, **mpl_kwargs)
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/matplotlib/backend_bases.py", line 2261, in print_figure
    **kwargs)
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/matplotlib/backends/backend_agg.py", line 511, in print_png
    FigureCanvasAgg.draw(self)
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/matplotlib/backends/backend_agg.py", line 431, in draw
    self.figure.draw(self.renderer)
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/matplotlib/artist.py", line 55, in draw_wrapper
    return draw(artist, renderer, *args, **kwargs)
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/matplotlib/figure.py", line 1475, in draw
    renderer, self, artists, self.suppressComposite)
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/matplotlib/image.py", line 141, in _draw_list_compositing_images
    a.draw(renderer)
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/matplotlib/artist.py", line 55, in draw_wrapper
    return draw(artist, renderer, *args, **kwargs)
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/matplotlib/axes/_base.py", line 2607, in draw
    mimage._draw_list_compositing_images(renderer, self, artists)
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/matplotlib/image.py", line 141, in _draw_list_compositing_images
    a.draw(renderer)
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/matplotlib/artist.py", line 55, in draw_wrapper
    return draw(artist, renderer, *args, **kwargs)
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/matplotlib/image.py", line 593, in draw
    renderer, renderer.get_image_magnification())
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/matplotlib/image.py", line 841, in make_image
    unsampled=unsampled)
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/matplotlib/image.py", line 407, in _make_image
    vmid = self.norm.vmin + dv / 2
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/yt/units/yt_array.py", line 1311, in __array_ufunc__
    inps, units, ufunc, ret_class)
  File "/turquoise/usr/projects/cosmology/miniconda3/lib/python3.6/site-packages/yt/units/yt_array.py", line 168, in handle_preserve_units
    raise YTUnitOperationError(ufunc, *units)
yt.utilities.exceptions.YTUnitOperationError: The <ufunc 'add'> operator for YTArrays with units (cm/s) and (dimensionless) is not well defined.