fix flake8 issues

Author: emilyfy

lib/mpl_toolkits/mplot3d/axes3d.py

@@ -1247,9 +1247,9 @@ def _on_move(self, event):
             dy = 1-((h - dy)/h)
             elev, azim = np.deg2rad(self.elev), np.deg2rad(self.azim)
             # project xv, yv, zv -> xw, yw, zw
-            dxx = (maxx-minx) * ( dy * np.sin(elev) * np.cos(azim) + dx * np.sin(azim) )
-            dyy = (maxy-miny) * ( - dx * np.cos(azim) + dy * np.sin(elev) * np.sin(azim) )
-            dzz = (maxz-minz) * ( - dy * np.cos(elev) )
+            dxx = (maxx-minx)*(dy*np.sin(elev)*np.cos(azim) + dx*np.sin(azim))
+            dyy = (maxy-miny)*(-dx*np.cos(azim) + dy*np.sin(elev)*np.sin(azim))
+            dzz = (maxz-minz)*(-dy*np.cos(elev))
             # pan
             self.set_xlim3d(minx + dxx, maxx + dxx)
             self.set_ylim3d(miny + dyy, maxy + dyy)