Please convert the Oracle syntax into qlik view expression

[#1]

nvl (decode(sign(OS),-1,0,OS),0)

[Gysbert_Wassenaar]

rangemax(0,OS)

[#3]

NVL-is for checking null values

IF decode(sign(OS))=-1 then 0 else OS

IF NULL = 0

Please convert into Qlik view expression

[sujeetsingh]

if(If(OS<0,0,OS)=null(),0,If(OS<0,0,OS))