Matrix Subtracting column Values

Euro0681 , Assume you are using a measure and only 2 dates are selected

then you can switch total using isinscope

new measure =
var _max = maxx(allselected(Date),Date[Date])
var _min = minx(allselected(Date),Date[Date])
return

if(isinscope(Date[Date]), [Measure],
calculate( [Measure], filter('Date', 'Date'[Date] =_min )) - calculate( [Measure], filter('Date', 'Date'[Date] =  =_max)) )

if they are month

new measure =
var _max = maxx(allselected(Date),Date[Date])
var _min = minx(allselected(Date),Date[Date])
return

if(isinscope(Date[Date]), [Measure],
calculate( [Measure], filter('date',eomonth( 'date'[Date],0) =eomonth(_min,0) )) - calculate( [Measure], filter('date', eomonth('date'[Date],0) = eomonth(_max,0) )) )