<div dir="ltr"><div>Hi people,<br><br></div>I have a physics question which comes from adding the gradient of gravitational potential. I want to use <img alt="g = -\nabla \phi" title="g = -\nabla \phi" class="" src="https://latex.codecogs.com/gif.latex?%5Cdpi%7B300%7D%5Cinline%09g%09=%09-%5Cnabla%09%5Cphi" id="l0.546695648047268" style="display: inline; vertical-align: -3.3px;" height="15" width="67"> , where <img alt="\phi" title="\phi" class="" src="https://latex.codecogs.com/gif.latex?%5Cdpi%7B300%7D%5Cinline%09%5Cphi" id="l0.9021949285488291" style="display: inline; vertical-align: -3.3px;" height="15" width="8"> stands for grav. potential. <br><div><br></div><div>I see in yt cookbook they add gradient to grav. potential</div><div><br></div><div> <b><span class="">ds</span> <span class="">=</span> <span class="">yt</span><span class="">.</span><span class="">load</span><span class="">(</span><span class="">"~/path to folder"</span><span class="">)</span></b></div><div><b><span class=""> </span><span class="">grad_fields</span> <span class="">=</span> <span class="">ds</span><span class="">.</span><span class="">add_gradient_fields</span><span class="">((</span><span class="">"gas"</span><span class="">,</span><span class="">"gravitational_potential"</span><span class="">))</span></b></div><div><span class=""><br></span></div><div><span class=""> now if I want to calculate the "g", do I just add </span></div><div><span class="">  </span></div><div><span class=""><b>dd= ds.all_data()<br></b></span></div><div><span class=""><b><br></b></span></div><div><b><span class=""> g_x = - dd</span><span class="">[</span><span class="">"gravitational_potential_gradient_x"</span><span class="">] </span></b></div><div><b><span class=""><br></span></b></div><div><b>I was wondering if that last line does stand for <img alt="g_{x} = -\nabla_{x} \phi" title="g_{x} = -\nabla_{x} \phi" class="va_li" src="https://latex.codecogs.com/gif.latex?%5Cdpi%7B300%7D%5Cinline%09g%5F{x}%09=%09-%5Cnabla%5F{x}%09%5Cphi" id="l0.5578024332104121" height="15" style="display: inline; vertical-align: -3.3px;" width="82"> </b></div><div><b><br></b></div><div><b>thanks</b></div><div><b>Tazkera</b></div></div>