>
<dd>   Perform a 3 dimensional weighted summation of named field </dd>
<dt>
<a href="#sum_field_2d_hemi">sum_field_2d_hemi</a>:</dt>
<dd>   Perform a 2 dimensional hemispherical summation of named field </dd>
<dt>
<a href="#diag_integral_output">diag_integral_output</a>:</dt>
<dd>   diag_integral_output determines if this is a timestep on which
   integrals are to be written. if not, it returns; if so, it calls
   write_field_averages. </dd>
<dt>
<a href="#diag_integral_end">diag_integral_end</a>:</dt>
<d