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1、文档供参考，可复制、编制，期待您的好评与关注！ _HELP函数集-abs(x) 绝对值arctan(x) 反正切cos(x) 传回馀弦函数值exp(x) e的x次幂frac(x) 取小数部分int(x) 取整ln(x) 自然对数sin(x) 传回正弦函数值 sqr(x) x*xsqrt(x) 平方根其它pred(x) pred(D)=C, pred(true)=1;succ(x) succ(Y)=Z, succ(pred(x)=xord(x) 求x在字符集中的序号,如ord(A)=65chr(x) chr(65)=Around(x) 四舍五入trunc(x) trunc(4.8)=4,trun
2、c(-3.6)=-3upcase(x) upcase(a)=Ahi(I) hi($2A30)=$2Alo(I) lo($2A30)=$30random(n) 产生0,n)间的随机整数sizeof(name) 求出某类型或变量在内存中占用的字节数swap(num) swap($3621)=$2136=Arithmetic routines数学运算=Abs绝对值-UnitSystem函数原型function Abs(X);说明X为整数or实数.范例var r: Real; i: Integer;begin r := Abs(-2.3); 2.3 i := Abs(-157); 157 end;-A
3、rcTan三角函数-范例Cosvar R: Extended;begin R := Cos(Pi);end;-Sin-范例var R: Extended; S: string;begin R := Sin(Pi); Str(R:5:3, S); Canvas.TextOut(10, 10, The Sin of Pi is + S);end;-UnitSystem函数原型function ArcTan(X: Extended): Extended;函数原型function Cos(X: Extended): Extended;函数原型function Sin(X: Extended): Ext
4、ended;-说明X为径度.Tan(x) = Sin(x) / Cos(x)ArcSin(x) = ArcTan (x/sqrt (1-sqr (x)ArcCos(x) = ArcTan (sqrt (1-sqr (x) /x)左边这三个不是函数,而是右边运算求得.范例var R: Extended;begin R := ArcTan(Pi);end;范例var R: Extended; S: string;begin R := Sin(Pi); Str(R:5:3, S); Canvas.TextOut(10, 10, The Sin of Pi is + S);end;-Frac求一个实数
5、的小数部份-UnitSystem函数原型function Frac(X: Real): Real;说明X为实数.范例var R: Real;begin R := Frac(123.456); 0.456 R := Frac(-123.456); -0.456 end;-Int求一个实数的整数部份-UnitSystem函数原型function Int(X: Real): Real;说明X为实数.范例var R: Real;begin R := Int(123.456); 123.0 R := Int(-123.456); -123.0 end;-Pi就是数学的Pi-UnitSystem函数原型f
6、unction Pi: Extended;说明它是一个函数,但我们就把它当作是预设的变数来用吧!Pi= 3.1415926535897932385-SqrX的平方-范例var S, Temp: string;begin Str(Sqr(5.0):3:1, Temp); S := 5 squared is + Temp + #13#10; Str(Sqrt(2.0):5:4, Temp); S := S + The square root of 2 is + Temp; MessageDlg(S, mtInformation, mbOk, 0);end;-SqrtX的平方根-UnitSystem
7、函数原型function Sqr(X: Extended): Extended;函数原型function Sqrt(X: Extended): Extended;范例var S, Temp: string;begin Str(Sqr(5.0):3:1, Temp); S := 5 squared is + Temp + #13#10; Str(Sqrt(2.0):5:4, Temp); S := S + The square root of 2 is + Temp; MessageDlg(S, mtInformation, mbOk, 0);end;-Ln自然对数-范例var e : real
8、; S : string;begin e := Exp(1.0); Str(ln(e):3:2, S); S := e = + FloatToStr(e) + ; ln(e) = + S; Canvas.TextOut(10, 10, S);end;-Exp指数-UnitSystem函数原型function Ln(X: Real): Real;函数原型function Exp(X: Real): Real;范例var e : real; S : string;begin e := Exp(1.0); Str(ln(e):3:2, S); S := ln(e) = + S; Canvas.Tex
9、tOut(10, 10, S);end;- Date and time routines日期及时间函数-Date传回目前的日期UnitSysUtils函数原型function Date: TDateTime;范例procedure TForm1.Button1Click(Sender: TObject);begin Label1.Caption := Today is + DateToStr(Date);end;-DateTimeToStr日期时间转换成内定型字串(1996/12/20 09:12:20 PM)-UnitSysUtils函数原型function DateTimeToStr(DateTime: TDateTime): string;范例procedure TForm1.Button1Click(Sender: TObject);begin Label1.Caption := DateTimeToStr(Now);end;-
