<html><body><div style="font-family: arial, helvetica, sans-serif; font-size: 12pt; color: #000000"><div><br data-mce-bogus="1"></div><div>Dear all,</div><div><br data-mce-bogus="1"></div><div>Assume I have a thorn mounted on Carpet, completely unrelated to any GR thorn (say my_wavetoy) .<br></div><div><br data-mce-bogus="1"></div><div>Is there a way to estimate the integral of a grid function on every slice of z=constant?</div><div><br data-mce-bogus="1"></div><div>This reminds me the outflow thorn that is capable of estimating the integral of fluxes (grid functions) across a spherical surface.</div><div><br data-mce-bogus="1"></div><div>I wonder whether there is something similar to integrate a flux (a given grid function of my choice) across z=constant planes:</div><div><br data-mce-bogus="1"></div><div>- perhaps a reduction operator from Carpet</div><div>- a similar thorn to outflow</div><div><br data-mce-bogus="1"></div><div>Thanks in advance,</div><div>Francisco</div><div><br data-mce-bogus="1"></div></div></body></html>