<div dir="ltr">Thanks for the reply, Jeff! <div><br></div><div>That was my guess as well. I thought it was just strange the fact that Grads truncates when plotting te field but doesn´t do it when setting a single point...</div><div><br></div><div>Regards,<br><div><br></div></div></div><div class="gmail_extra"><br clear="all"><div><div class="gmail_signature">--<br>Helio</div></div>
<br><div class="gmail_quote">On Sat, Apr 30, 2016 at 4:52 PM, Jeff Duda <span dir="ltr"><<a href="mailto:jeffduda319@gmail.com" target="_blank">jeffduda319@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>My only guess is that since the differences are so small, Grads just truncates them to zero.<br><br></div>Jeff Duda<br></div><div class="gmail_extra"><br><div class="gmail_quote"><div><div class="h5">On Fri, Apr 29, 2016 at 2:36 PM, Helio Camargo <span dir="ltr"><<a href="mailto:heliocamargo@gmail.com" target="_blank">heliocamargo@gmail.com</a>></span> wrote:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5"><div dir="ltr"><div><br></div><div>I´m performing the following expressions over time 1 of a 50 ensemble member run:</div><div><br></div><div>'set t 1 last'</div><div>'set e 1 last'</div><div>'define ens = tpratesfc.1 '</div><div><br></div><div>1) 'define smens = sum(ens,e=1,e=50)'</div><div>2) 'define 'smensmsk = maskout(sum(ens,e=1,e=50),sum(ens,e=1,e=50)-0)'</div><div>3) 'define 'smensmskcnst = const(maskout(sum(ens,e=1,e=50),sum(ens,e=1,e=50)-0),0,-u)'</div><div><br></div><div>'set t 1'</div><div><br></div><div>For some reason, for t=1, expression 1, yelds small negative values (smens.gif, attached). Expressions 2 and 3 should set undef to these negative values and set 0 for these undef grid points respectively. Looking at the figures smensmsk.gif and smensmskcnst.gif, these operations seem to work perfectly<br></div><div><br></div><div>And setting lon/lat to a point where the above operations should influence, is consistent with the figures above:</div><div>Lon = 298.442 Lat = -28.8304</div><div><b>ga-> d smens<br></b></div><div><b>Result value = -8.33652e-19</b></div><div><br></div><div><b>ga-> d smensmsk</b></div><div><b>Result value = -9.99e+08</b></div><div><br></div><div><b>ga-> d smensmskcnst</b></div><div><b>Result value = 0</b></div><div><br></div><div><b>* differences also show expected result</b></div><div><b>> operation 2 - operation 1</b></div><div><div>ga-> d smensmsk-smens</div><div>Result value = -9.99e+08</div></div><div><br></div><div><b>> operation 3 - operation 2</b></div><div><div>ga-> d smensmskcnst-smensmsk</div><div>Result value = -9.99e+08</div></div><div><br></div><div><b>> operation 3 - operation 1</b></div><div><div>ga-> d smensmskcnst-ens</div><div>Result value = 1.9073e-20</div></div><div><br></div><div>However, making FIELD diferences between defined expression 3 and defined expression 1 results "Constant Field=0" (diff_smensmskcnstsmens.gif). </div><div><br></div><div>Can anyone explain why this is happening?</div><div><br></div><div>Thanks in advance for your patience.</div><div><div>--<br>Helio</div></div>
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<br></blockquote></div><span class="HOEnZb"><font color="#888888"><br><br clear="all"><br>-- <br><div>Jeff Duda<br>Graduate research assistant<br>University of Oklahoma School of Meteorology<br>Center for Analysis and Prediction of Storms<br></div>
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