How do I remove negative numbers from an eval?

[matt]

I have a search which runs an eval statement. The problem is every couple of times a day the numbers its pulling (they are incremental numbers) are reset. This of course means the last number received is higher then the first number received in the search and results in a negative value. I want to throw this number out entirely. How do I go about this?

Example Problem:

eval FOO = firstFOO-lastFOO
Where firstFOO=10 and lastFOO is 1024
Foo will now equal -1014 which completely messes up the graphs.

Usually this is an incrementing number, but this counter gets reset when the application does.

[araitz · Accepted solution]

| eval FOO = if(firstFOO<lastFOO,null,firstFOO-lastFOO)