Maximum on summary fields

Ia have several Summary fields in my report that I need to compare and get maximum -

I would like to do the following if possible;

maximum of these - Sum ({@JTD Cost}, {JCT_CURRENT__TRANSACTION.Job}),Sum ({@JTD Committed}, {JCT_CURRENT__TRANSACTION.Job}),Sum ({@Forecast}, {JCT_CURRENT__TRANSACTION.Job})