domains
   list = real*
 predicates
   r_to_c(list,list)
   mult(real,list,list)
   add(list,list,list)
clauses
  r_to_c([X],[1,Y]):- Y=-X.
  r_to_c([H|T],L):- r_to_c(T,L1), K=-H, 
 mult(K,L1,L11),                      
 add([0|L11],L1,L).           
  mult(_,[],[]).
  mult(K,[H|T1],[R|T2]):- R=H*K, mult(K,T1,T2).
  add([H],[],[H]).
  add([H|T1],[R|T2],[F|T3]):- F=H+R,
  add(T1,T2,T3).  
? r_to_c([-3,2],X)