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<p class="MsoNormal"><span style="color:#1F497D">Bill,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">If you have enough data points you should be able to generate similar curves in excel using the LINEST command. It spits out the same trendline coefficients that you would get if you graph data then add a trendline.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">It’s set up like this :<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">=LINEST(y-values,x-values,true,true)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">This will spit out the m and b in y=mx+b.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Cubic looks like this <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">=LINEST(y-values,x-values^{1,2,3),true,true)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">This will give you y=ax^3+bx^2+cx+d<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">You can also use it to do bi-quadratic, which looks like this:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">=linest(y-values,x1-values^{0,0,1,2)*x2-values^{1,2,0,0),true,true)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">The form here is : y = a*x1+b*x1^2+c*x2+d*x2^2+e<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">If you want to add a x1*x2 term you change the x value definition to : x1-values^{0,0,1,1,2)*x2-values^{1,2,1,0,0).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I think it’s the same idea for bi-linear but I haven’t tried it.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I was looking into how to do this a couple weeks ago and there is a decent amount of info on excel msg boards on how to generate complex regressions. Also, it has to be entered as a array, and the 2<sup>nd</sup>
true statement allows it to spit out statistics about the curve fit so you can check the R<sup>2</sup> value.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Hope that helps.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Brendan Hall, PE, LEED AP </span>
<span style="font-size:8.0pt;color:#1F497D">BD+C</span><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Engineer, Mechanical<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:13.5pt;font-family:"Arial","sans-serif";color:red">karpinski<br>
</span><span style="font-size:7.5pt;font-family:"Arial","sans-serif";color:#1F497D">ENGINEERING<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D">3135 Euclid Avenue</span><span style="font-family:"Arial","sans-serif";color:#1F497D"><br>
</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D">Cleveland, OH 44115</span><span style="font-family:"Arial","sans-serif";color:#1F497D"><br>
</span><b><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#C00000">P</span></b><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D"> 216.391.3700 x 3111<o:p></o:p></span></p>
<p class="MsoNormal"><b><span lang="SV" style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#C00000">E</span></b><b><span lang="SV" style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D"> </span></b><span lang="SV" style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D"> </span><u><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:blue"><a href="mailto:bhall@karpinskieng.com"><span lang="SV">bhall@karpinskieng.com</span></a></span></u><span lang="SV" style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D"><br>
</span><b><span lang="SV" style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#C00000">W</span></b><span lang="SV" style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D">
</span><u><span lang="SV" style="font-size:10.0pt;font-family:"Arial","sans-serif";color:blue">www.</span></u><u><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:blue"><a href="http://www.karpinskieng.com/" title="http://www.karpinskieng.com/"><span lang="SV">karpinskieng.com</span></a></span></u><span lang="SV" style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">
<a href="mailto:equest-users-bounces@lists.onebuilding.org">equest-users-bounces@lists.onebuilding.org</a> [<a href="mailto:equest-users-bounces@lists.onebuilding.org">mailto:equest-users-bounces@lists.onebuilding.org</a>]
<b>On Behalf Of </b>Bishop, Bill<br>
<b>Sent:</b> Tuesday, March 05, 2013 4:43 PM<br>
<b>To:</b> <a href="mailto:equest-users@lists.onebuilding.org">equest-users@lists.onebuilding.org</a><br>
<b>Subject:</b> [Equest-users] Performance (curve) anxiety<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Performance curves are defined by an INPUT-TYPE of COEFFICIENTS or DATA. I am creating several performance curves based on manufacturer data points, but would like to define them with COEFFICIENTS to save space in the input file.<o:p></o:p></p>
<p class="MsoNormal">Can someone walk me through a method to determine coefficients in Excel, or using another add-in or program, for the following CURVE-FIT TYPEs?<o:p></o:p></p>
<p class="MsoNormal"> <span style="color:black">TYPE = BI-LINEAR-T<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:black"> TYPE = BI-QUADRATIC-T<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:black"> TYPE = CUBIC<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:black">Yes, eQUEST generates the coefficients when you enter data points, but I see no way to copy them to then turn around and define the curve using the coefficients.<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal">Bill<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><a href="mailto:wbishop@pathfinder-ea.com"><span style="text-decoration:none"><img border="0" width="480" height="114" id="Picture_x0020_1" src="cid:image001.jpg@01CE19C7.E3214DC0" alt="Senior Energy Engineer 28Jun2012"></span></a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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