add double jtutil::signum(double x)

git-svn-id: http://svn.einsteintoolkit.org/cactus/EinsteinAnalysis/AHFinderDirect/trunk@261 f88db872-0e4f-0410-b76b-b9085cfa78c5

1 files changed, 17 insertions, 0 deletions

diff --git a/src/jtutil/miscfp.cc b/src/jtutil/miscfp.cc
index baf164e..7b151c1 100644
--- a/src/jtutil/miscfp.cc
+++ b/src/jtutil/miscfp.cc
@@ -1,6 +1,7 @@
 // miscfp.cc -- misc floating-point functions
 
 //
+// signum - sign of a floating point number
 // hypot3 - 3D Euclidean distance
 // arctan_xy - 4-quadrant arc tangent
 // modulo_reduce - reduce an angle modulo 2*pi radians (360 degrees)
@@ -13,6 +14,22 @@
 //******************************************************************************
 
 //
+// This function computes the floating point "signum" function (as in APL),
+// signum(x) = -1.0, 0.0, or +1.0, according to the sign of x.
+//
+namespace jtutil
+	  {
+double signum(double x)
+{
+if (x == 0.0)
+   then return 0.0;
+   else return (x > 0.0) ? 1.0 : -1.0;
+}
+	  };
+
+//******************************************************************************
+
+//
 // This function computes the 3-dimensional Euclidean distance,
 // analogously to the standard math library function  hypot(2) .
 //