TAChart: Add SafeEqual to TAMath for non-crashing number comparison with NaN.

git-svn-id: trunk@51484 -

components/tachart/tamath.pas

@@ -30,6 +30,7 @@ function SafeInfinity: Double; inline;
 function SafeInRange(AValue, ABound1, ABound2: Double): Boolean;
 function SafeMin(A, B: Double): Double;
 function SafeNan: Double; inline;
+function SafeEqual(A, B: Double): Boolean;
 
 implementation
 
@@ -177,6 +178,20 @@ begin
   {$POP}
 end;
 
+function SafeEqual(A, B: Double): Boolean;
+var
+  ANaN, BNaN: Boolean;
+begin
+  ANaN := IsNaN(A);
+  BNaN := IsNaN(B);
+  if ANaN and BNaN then
+    Result := true
+  else if ANaN or BNaN then
+    Result := false
+  else
+    Result := A = B;
+end;
+
 // Convert double value to integer 2's complement representation.
 // Difference between resulting integers can be interpreted as distance in ulps.
 function Ulps(AX: Double): Int64; inline;