FileMaker Pro Custom Functions

/* no error checking deliberate for speed... results in correct fraction in format "(-)e/f" - uses GCF to get simplest possible... */ Let ( [ // error check _operator = Filter(_operator ; "+-/*"); _div1 = Position ( _a_b ; "/" ; 0 ; 1 ) ; _div2 = Position ( _c_d ; "/" ; 0 ; 1 ) ] ; if ( ( length ( _operator ) = 1 ) and ( _div1 > 1 ) and ( _div2 > 1 ) ; Let ( [ // get a,b a = Left ( _a_b ; _div1 - 1 ) ; b = Middle ( _a_b ; _div1 + 1 ; 999 ) ; // get c,d c = Left ( _c_d ; _div2 - 1 ) ; d = Middle ( _c_d ; _div2 + 1 ; 999 ) ; // handle them _e = Case ( _operator = "-" ; ((a*d)-(c*b)) ; _operator = "+" ; ((a*d)+(c*b)) ; _operator = "*" ; a*c ; _operator = "/" ; a * d ) ; _f = Case ( _operator = "/" ; b * c ; b*d ) ; _gcf = GCF ( _e ; _f ) ] ; (_e/_gcf) & "/" & (_f/_gcf) ) // end sub let ) // end if ) // end grand let
 Then copy & paste into FileMaker Advanced's Edit Custom Function window.