How can I build a chart that show the difference between two fields?

[jfallon1]

index=app sourcetype=application1 source=server1production with this search I get back two field Baseprice and finalprice. How can I build a chart that show the difference between finalprice and baseprice?

[Sukisen1981]

not cleat what you want, I am guessing you want some sort of final price (y axis) over baseprice(xaxis) and also the difference.
If so, try this |chart values( finalprice) by baseprice| eval diff=finalprice-baseprice
Use format option in visualization > select diff as chart overlay
But as @adonio says, are your fields numerical?

[adonio]

are those numeric fields? meaning are the values for these fields are numbers?
if so, try this ... your search ... | eval diff = finalprice - baseprice | chart ...