<div dir="ltr">NCL uses a f77 subroutine based upon a code originally created by the USA's National Climate Data Center (now known as the <a href="https://en.wikipedia.org/wiki/National_Centers_for_Environmental_Information" title="National Centers for Environmental Information">National Centers for Environmental Information</a> (NCEI). It contains the following code comments.<br><sup id="cite_ref-ncei.noaa.gov_2-0" class=""></sup><div><br>c OUTPUT: par1,par2,par3 parameters (mean, s.d., skewness) of<br>c Pearson Type III distribution used to<br>c fit the input data > 0<br>c xmom1,xmom2,xmom3 l-moments of the input data > 0<br>c pzero relative frequency of input data = 0<br><br></div><div>So, without looking at the code in detail, I'd say 0s are ignored.<br><br></div><div>If you want to see the code, I have placed the code at<br></div><div><br><a href="http://www.cgd.ucar.edu/~shea/spi3.f">http://www.cgd.ucar.edu/~shea/spi3.f</a><br><br></div><div>Good luck<br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Jun 29, 2016 at 7:39 AM, Kritanai Torsri (HAII User) <span dir="ltr"><<a href="mailto:kritanai@haii.or.th" target="_blank">kritanai@haii.or.th</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div style="font-family:arial,helvetica,sans-serif;font-size:12pt;color:#000000"><div>Dear ALL,<br></div><div><br></div><div>Can any one help me to clarify how "dim_spi_n" deals with zero precipitation for both fitting with 2-param Gamma distribution and Pearson Type 3?</div><div><br></div><div>and how it maps cumulative distribution function (cdf) into SPI values?</div><div><br></div><div>Thanks in advance.</div><div><br></div><div>BRGs,<br></div><div><br></div><div>Kritanai T.<br></div><div><br></div><div> <br></div></div></div><br>_______________________________________________<br>
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