code 35173;
    procedure BESS K01(X, K0, K1); value X; real X, K0, K1;
    if X <= 1.5 then 
    begin integer K; real C, D, R, S, SUM0, SUM1, T,
        TERM, T0, T1;
        SUM0:= D:= LN(2/X) -.5772156649015328606;
        SUM1:=    C:= -1 -2    * D; R:= TERM:= 1; T:= X * X/4;
        for K:= 1,K+1 while ABS(T0/SUM0) + ABS(T1/SUM1) >
        "-15 do 
        begin  TERM:= T * TERM * R * R; D:= D + R;
            C:= C - R; R:= 1/(K+1); C:= C - R;
            T0:= TERM * D; T1:= TERM * C * R;
            SUM0:= SUM0 + T0; SUM1:= SUM1 + T1
        end;
        K0:= SUM0; K1:= (1 + T * SUM1) / X
    end else 
    begin real EXPX;
        EXPX:= EXP(- X);
        NONEXP BESS K01(X, K0, K1); K1:= EXPX * K1; K0:= K0 * EXPX
    end BESS K01;
        eop