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--- root:setaxisrange [2010/11/09 16:08] – created nchiap
+++ root:setaxisrange [2011/05/11 15:35] – added solution for my latest problem nchiap
@@ Line 1: / Line 1: @@
 ====== Set Display Range of Axis ======
+The normal way to change the display range of an axis is:
 <code C++>
 histogram->GetYaxis()->SetRangeUser(lower,upper);
+</code>
+but there are several situations where this fails. See below for help in these cases.
+===== Y Axis of a normalized Histogram =====
+Assume you have a histogram which has been normalized it with **hist->SetNormFactor(1)**.
+When your Y-axis will show values between 0 and 1.
+Trying to set the Y range using these values, eg. **SetRangeUser(0.01, 0.2)**, will fail however.
+You still need to give the range in the original unnormalized units.
+You can scale normalized units back with:
+<code C++>
+Double_t scaleY = hist->GetEntries()/hist->GetNormFactor();
+hist->GetYaxis()->SetRangeUser(normalizedLower*scaleY,normalizedUppe*scaleY);
 </code>

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