Add the greater of two numbers

I am creating a document and the last calculation I need is the addition of the higher of two fields. What script do I need to add in. 

 The three fields are below. I need to add Total Income to the higher or either Income From Asset Value or Imputed Value and if both are 0 then 0 or no change. 

var fld1=this.getField("Income Total").value;
var fld2=this.getField("Income From Asset Value").value;
var fld3=this.getField("Imputed Value").value;