bessy.txt

《Delphi常用数值算法集》的配书源码

Function BESSY(var N:integer; X:real):real;
var
    TOX,BY,BYM,BYP:real;j:integer;
begin
    If N < 2 Then
        ShowMessage('bad argument N in BESSY');
    TOX:= 2 / X;
    By:= BESSY1(X);
    BYM:= BESSY0(X);
    For J:= 1 To N - 1 do
    begin
        BYP:= J * TOX * By - BYM;
        BYM:= By;
        By:= BYP;
    end;
    BESSY:= By;
end;