question: public String checkParamsNonNegative ( ) { String ret = "" ; if ( param1 < 0 ) { ret = ret . concat ( pdf . getParam1Name ( ) + " is negative. \n" ) ; } if ( param2 < 0 ) { ret = ret . concat ( pdf . getParam2Name ( ) + " is negative. \n" ) ; } if ( upperBound < 0 ) { ret = ret . concat ( "Upper boundary is negative. \n" ) ; } if ( lowerBound < 0 ) { ret = ret . concat ( "Lower boundary is negative. \n" ) ; } return ret ; }
target:  Checks to make sure that there are no negative parameters.