bessy1.txt

用于开发税务票据管理的软件

Function BESSY1(X:real):real;
var
    AAA,BBB,CCC,Z,Y,XX:real;
const
    P1 = 1;                    P2 = 0.183105e-2;
    P3 = -0.3516396496e-4;     P4 = 0.2457520174e-5;
    P5 = -0.240337019e-6;
    Q1 = 0.04687499995;        Q2 = -0.2002690873e-3;
    Q3 = 0.8449199096e-5;      Q4 = -0.88228987e-6;
    Q5 = 0.105787412e-6;
    R1 = -4.900604943e12;      R2 = 1.27527439e12;
    R3 = -5.153438139e10;      R4 = 7.349264551e8;
    R5 = -4237922.726;         R6 = 8511.937935;
    S1 = 2.49958057e13;        S2 = 4.244419664e11;
    S3 = 3.733650367e9;        S4 = 2.245904002e7;
    S5 = 102042.605;           S6 = 354.9632885;
    S7 = 1;
begin
    If X < 8 Then
    begin
        Y:= X * X;
        AAA:=R1 + Y * (R2 + Y * (R3 + Y * (R4 + Y * (R5 + Y * R6))));
        BBB:=S4 + Y * (S5 + Y * (S6 + Y * S7));
        BBB:=S1 + Y * (S2 + Y * (S3 + Y * BBB));
        CCC:=BESSJ1(X) * Ln(X) - 1/ X;
        BESSY1:=X * AAA / BBB + 0.636619772 * CCC;
    end
    Else
    begin
        Z:=8 / X;
        Y:=Z * Z;
        XX:=X - 2.356194491;
        AAA:=Sqrt(0.636619772 / X);
        BBB:=P1 + Y * (P2 + Y * (P3 + Y * (P4 + Y * P5)));
        CCC:=Q1 + Y * (Q2 + Y * (Q3 + Y * (Q4 + Y * Q5)));
        BESSY1:=AAA * (Sin(XX) * BBB + Z * Cos(XX) * CCC);
    end;
end;