total newbie trying to work through the rails tutorial on lynda.com

The code is really short and exactly the way it is on the video, yet I can't get my page to render the partial. When I pull run it on the server it does not render the partial at all, but just skips it. No error messages. Thanks in advance

this is edit.html.erb

&lt;%= link_to("&lt;&lt; Back to List", {:action =&gt; 'list'}, :class =&gt; 'back=link')%&gt;

&lt;div class="subject edit"&gt;
    &lt;h2&gt;Edit Subject&lt;/h2&gt;

    &lt;%= form_for(:subject, :url =&gt; {:action =&gt; 'update', :id=&gt;@subject.id}) do |f| %&gt;

        &lt;% render :partial =&gt; 'form', :locals =&gt; {:f =&gt; f} %&gt;

        &lt;div class="form-buttons"&gt;
            &lt;%= submit_tag("Update Subject")%&gt;
        &lt;/div&gt;

    &lt;% end %&gt;
&lt;/div&gt;


and this is _form.html.erb

&lt;table summary="Subject form fields"&gt;
    &lt;tr&gt;
        &lt;th&gt;Name&lt;/th&gt;
        &lt;td&gt;&lt;%= f.text_field(:name) %&gt;&lt;/td&gt;
    &lt;/tr&gt;
    &lt;tr&gt;
        &lt;th&gt;Position&lt;/th&gt;
        &lt;td&gt;&lt;%= f.text_field(:position) %&gt;&lt;/td&gt;
    &lt;/tr&gt;
    &lt;tr&gt;
        &lt;th&gt;Visible&lt;/th&gt;
        &lt;td&gt;&lt;%= f.text_field(:visible) %&gt;&lt;/td&gt;
    &lt;/tr&gt;
&lt;/table&gt;



Question: ListDensityPlot performance when scaling axes
Answer: Too long for a comment:

Packing the data, as @0x4A4D suggests, seems to "fix" the problem, except in InterpolationOrder -&gt; 0.  See What is a Mathematica packed array? for an explanation of the importance of packed arrays.

TableForm[
 ParallelTable[
  Benchmark[data, n],
  {data,  Developer`ToPackedArray /@ N@{testdata, testdataPoints, testdataPoints2}},
  {n, 0, 2}], 
 TableHeadings -&gt; {{"Array", "Integer", "Float"}, {0, 1, 2}}]




This way is faster:

TableForm[
 Table[
  Timing[
   ifn = Interpolation[data, InterpolationOrder -&gt; n]; 
   DensityPlot[ifn[i, j],
    {i, -1, 1}, {j, -1, 1}, PlotPoints -&gt; 101, 
    ColorFunction -&gt; "Rainbow", PlotRange -&gt; Full]],
  {data, {testdataPoints2}}, {n, 0, 2}], 
 TableHeadings -&gt; {{"Float"}, {0, 1, 2}}]