1 files changed, 47 insertions, 0 deletions
diff --git a/src/svg/round.cpp b/src/svg/round.cpp
new file mode 100644
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+++ b/src/svg/round.cpp
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+/////////////////////////////////////////////////////////////////////////
+//                               ftos.cc
+//
+// Copyright (c) 1996-2003 Bryce W. Harrington  [bryce at osdl dot org]
+//
+//-----------------------------------------------------------------------
+// License:  This code may be used by anyone for any purpose
+//           so long as the copyright notices and this license
+//           statement remains attached.
+//-----------------------------------------------------------------------
+// This routine rounds a double using the "rounding rule", as expressed
+// in _Advanced Engineering Mathematics_ by Erwin Kreyszig, 6th ed., 
+// John Wiley & Sons, Inc., 1988, page 945.
+//
+// Discard the (k+1)th and all subsequent decimals.
+//  (a) If the number thus discarded is less than half a unit in the
+//      kth place, leave the kth decimal unchanged ("rounding down")
+//  (b) If it is greater than half a unit in the kth place, add one
+//      to the kth decimal ("rounding up")
+//  (c) If it is exactly half a unit, round off to the nearest *even* 
+//      decimal.
+//  Example:  Rounding off 3.45 and 3.55 by one decimal gives 3.4 and
+//      3.6, respectively.
+//  Rule (c) is to ensure that in discarding exactly half a decimal,
+//      rounding up and rounding down happens about equally often,
+//      on the average.
+///////////////////////////////////////////////////////////////////////
+#include <math.h>
+
+double rround(double x)
+{
+	double xlow = floor(x);
+	if (x - xlow != 0.5000)
+		return floor(x + 0.5000);
+	else if ( floor(x/2.0) == xlow/2.0)
+		return xlow;
+	else
+		return xlow++;		
+}
+
+// This version allows rounding to a specific digit
+double rround(double x, int k)
+{
+	if (k==0) return rround(x);
+	else return rround(x*pow(10,k)) / pow(10,k);
+}
+