code 31092;
real procedure FOUSER (N,THETA,A);
value N,THETA;integer N;real THETA;array A;
begin integer K;real C,CC,LAMBDA,H,DUN,UN,UN1,C2,S2;
   C:=COS(THETA);
   if C<-.5then 
   begin C2:=COS(THETA/2);LAMBDA:=4*C2**2;UN:=DUN:=0;
          for K:=N"STEP"-1until 0do 
          begin UN:=DUN-UN;
                 DUN:=LAMBDA*UN-DUN+A[K]
          end;FOUSER :=DUN+2*C2*(SIN(THETA/2)-C2)*UN
   end else if C> .5then 
   begin S2:=SIN(THETA/2);LAMBDA:=-4*S2*S2;UN:=DUN:=0;
          for K:=N"STEP"-1until 0do 
          begin UN:=DUN+UN;
                 DUN:=LAMBDA*UN+DUN+A[K]
          end;FOUSER :=DUN+2*S2*(S2+COS(THETA/2))*UN
   end else 
   begin CC:=C+C;UN:=UN1:=0;
          for K:=N"STEP"-1until 1do 
          begin H:=CC*UN-UN1+A[K];
                 UN1:=UN;UN:=H
          end;FOUSER :=A[0]-UN1+(C+SIN(THETA))*UN
   end 
end FOUSER;
        eop