March 2014 update

Task/Safe-addition/AutoHotkey/safe-addition.ahk

@@ -0,0 +1,14 @@
+Msgbox % IntervalAdd(1,2) ; [2.999999,3.000001]
+
+SetFormat, FloatFast, 0.20
+Msgbox % IntervalAdd(1,2) ; [2.99999999999999910000,3.00000000000000090000]
+
+;In v1.0.48+, floating point variables have about 15 digits of precision internally
+;unless SetFormat Float (i.e. the slow mode) is present anywhere in the script.
+;In that case, the stored precision of floating point numbers is determined by A_FormatFloat.
+;As there is no way for this function to know whether this is the case or not,
+;it conservatively uses A_FormatFloat in all cases.
+IntervalAdd(a,b){
+	err:=0.1**(SubStr(A_FormatFloat,3) > 15 ? 15 : SubStr(A_FormatFloat,3))
+	Return "[" a+b-err ","a+b+err "]"
+}