Delphi中的算术运算函数

                            Abs
 Ceil
 Exp
 Floor
 frac
 
Frexp
 int
 intpower
 Ldexp
 max
 
min
 pi poly power round 
sqrt trunc sqr   
 
函数名 ABS 
简要介绍: Returns an absolute value. (取绝对值) 
所属单元: System 
定义: function Abs(X); 
详细解释:
 Abs returns the absolute value of the argument, X.
X is an integer-type or real-type expression.
(Abs函数用于返回变量X的绝对值,X可以是一个整形的变量或实数型的变量) 
 返回
 
函数名 ceil 
简要介绍: Rounds variables up toward positive infinity. 
所属单元: Math 
定义: function Ceil(X: Extended):Integer 
详细解释: Call Ceil to obtain the lowest integer greater than or equal to X. The absolute value of X must be less than MaxInt. For example:
Ceil(-2.8) = -2
Ceil(2.8) = 3
Ceil(-1.0) = -1 
(调用ceil函数,返回大于或等于x的最小整数值。X的绝对值一定要小于最大整数值。例如:
Ceil(-2.8) = -2

Ceil(2.8) = 3

Ceil(-1.0) = -1)
 
 返回 
函数名 Exp 
简要介绍: Returns the exponential of X.(Exp函数返回自然对数基底E的X次幂。) 
所属单元: System 
定义: function Exp(X: Real): Real; 
详细解释: 




Exp returns the value of e raised to the power of X, where e is the base of the natural logarithms.
(Exp返回e的X次幂的值,其中e是一个自然对数基底。)
 
范例: var
   e : real;
   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;
 
 返回
 
函数名 Floor 
简要介绍: Rounds variables toward negative infinity.(取小于给定值的最大整数) 
所属单元: Math 
定义: function Floor(X: Extended): Integer; 
详细解释: 




Call Floor to obtain the highest integer less than or equal to X. For example:

Floor(-2.8) = -3

Floor(2.8) = 2

Floor(-1.0) = -1

Note: The absolute value of X must be less than MaxInt. 

(使用Floor函数以取得小于等于X的最大的整数,如:
Floor(-2.8) = -3

Floor(2.8) = 2

Floor(-1.0) = -1

注意:X的绝对值必须小于整形数的最大值)
 
返回
 
函数名 Frac 
简要介绍: Returns the fractional part of a real number(返回一个实数的小数部分) 
所属单元: System 
定义: function Frac(X: Extended): Extended; 
详细解释: 




The Frac function returns the fractional part of the argument X.

X is a real-type expression. The result is the fractional part of X; that is, Frac(X) = X - Int(X). 

(Frac函数返回参数X的小数部分,X是一个实型数,该函数的作用等价于Frac(X)=X-Int(X)。)
 
范例: var
a,b:Real;
begin
a := 1.54;
b := frac(a);
end;
此时,a= 1.54,b=0.54
 
返回
 
函数名 Frexp 
简要介绍: Separates the Mantissa and Exponent of X(分解开X的尾数和指数。) 
所属单元: Math 
定义: procedure Frexp(X: Extended; var Mantissa: Extended; var Exponent: Integer) register; 
详细解释: 




Frexp returns the mantissa of X as Mantissa and the exponent as Exponent.(Frexp函数返回X的尾数用变量Mantissa和指数用变量Exponent)。
 
返回
 
函数名 int 
简要介绍: Returns the integer part of a real number.(返回一个实数类型的整数部分) 
所属单元: System 
定义: function Int(X: Extended): Extended; 
详细解释: 




Int returns the integer part of X; that is, X rounded toward zero. X is a real-type expression.(Int函数返回参数X的整数部分,X为实数类型,函数结果为X经过负向舍入(向0舍入)实数。) 

 
范例: var 

  R: Real;
begin
  R := Int(123.456);    { 123.0 }
  R := Int(-123.456);   { -123.0 }
end;

 
返回
 
函数名 Intpower 
简要介绍: Calculates the integral power of a base value.(计算基数的整数幂。) 
所属单元: Math 
定义: function IntPower(Base: Extended; Exponent: Integer): Extended register; 
详细解释: 




IntPower raises Base to the power specified by Exponent 

(计算基数的整数幂。base为基数,Exponent为指数)
 
范例:  
 
返回
 
函数名 Ldexp 
简要介绍: Calculates X * (2**P) 
所属单元: Math 
定义: function Ldexp(X: Extended; P: Integer): Extended register; 
详细解释: 



Ldexp returns X times (2 to the power of P).
(Ldexp计算X*(2**P),返回X的(2的P次幂)次幂。)
 
返回
 
函数名 Max 
简要介绍: Returns the greater of two numeric values.(取两个数中的最大值) 
所属单元: Math 
定义: function Max(A,B: Integer): Integer; overload;
function Max(A,B: Int64): Int64; overload;
function Max(A,B: Single): Single; overload;
function Max(A,B: Double): Double; overload;
function Max(A,B: Extended): Extended; overload;
 
详细解释: 



Call Max to compare two numeric values. Max returns the greater value of the two.
(返回两个数值中的最大值。调用Max比较两个数值。它返回二者中较大的一个值。)
 
返回
 
函数名 Min 
简要介绍: Returns the lesser of two numeric values.(取两个数的最小值) 
所属单元: Math 
定义: function Min(A,B: Integer): Integer; overload;
function Min(A,B: Int64): Int64; overload;
function Min(A,B: Single): Single; overload;
function Min(A,B: Double): Double; overload;
function Min(A,B: Extended): Extended; overload; 
详细解释: 



Call Min to compare two numeric values. Min returns the smaller value of the two.
(返回两个数值中的最小值。调用Max比较两个数值,它返回二者中较小的一个值。)
 
返回
 
函数名 pi 
简要介绍: Returns 3.1415926535897932385. (返回3.1415926535897932385.) 
所属单元: System 
定义: function Pi: Extended; 
详细解释: 



Use Pi in mathematical calculations that require pi, the ratio of a circle's circumference to its diameter. Pi is approximated as 3.1415926535897932385.
(使用Pi函数精确计算返回圆周率Pi,圆周率是一个圆的周长除以它的直径。Pi的值近似于3.1415926535897932385.)
 
返回
 
函数名 poly(本条翻译无把握) 
简要介绍: Evaluates a uniform polynomial of one variable at the value X. 
所属单元: Math 
定义: function Poly(X: Extended; const Coefficients: array of Double): Extended; 
详细解释: 



Call Poly to evaluate the polynomial represented by the Coefficients parameter at the point where the variable equals the value of the X parameter. The coefficients are ordered in increasing powers of X:

Coefficients[0] + Coefficients[1]*X + ... + Coefficients[N]*(X**N)
(Poly估计一个变量在同一多项式的X值。调用Poly评估由Coefficients参数表达的多项式在一位置的值等同于X参数的值。参数是顺序的以X的幂增加:Coefficients[0]+
coefficients[1]*X+…..+Cofficients[n]*[X**N])
 
返回
 
函数名 power 
简要介绍: Raises Base to any power.(取一个实数的幂) 
所属单元: Math 
定义: function Power(Base, Exponent: Extended): Extended; 
详细解释: 



Power raises Base to any power. For fractional exponents or exponents greater than MaxInt, Base must be greater than 0.
(返回一个实数的幂。 当指数Exponent为小数或大于MaxInt时,底数Base必须大于0.)
 
返回
 
函数名 Round 
简要介绍: Returns the value of X rounded to the nearest whole number.(对一个实数进行四舍五入) 
所属单元: System 
定义: function Round(X: Extended): Int64; 
详细解释: 



The Round function rounds a real-type value to an integer-type value.

X is a real-type expression. Round returns an Int64 value that is the value of X rounded to the nearest whole number. If X is exactly halfway between two whole numbers, the result is always the even number.

If the rounded value of X is not within the Int64 range, a run-time error is generated, which can be handled using the EInvalidOp exception.

(Round返回X向最近整数值的舍入。
函数将一个实型值舍入为一个整型值。X是一个实型表达式。Round返回一个长整型值,是离X最近的整数值。如果X是两个整数值的正中间,结果是绝对值最大的一个。如果X的舍入值不是在长整型范围内,一个运行时间错误将产生,可以使用EinvalidOp异常来处理)
 
范例: var

   S, T: string;

begin

   Str(1.4:2:1, T);
   S := T + ' rounds to ' + IntToStr(Round(1.4)) + #13#10;
   Str(1.5:2:1, T);
   S := S + T + ' rounds to ' + IntToStr(Round(1.5)) + #13#10;
   Str(-1.4:2:1, T);
   S := S + T + ' rounds to ' + IntToStr(Round(-1.4)) + #13#10;
   Str(-1.5:2:1, T);
   S := S + T + ' rounds to ' + IntToStr(Round(-1.5));
   MessageDlg(S, mtInformation, [mbOk], 0);
end;

 
返回
 
函数名 Sqr 
简要介绍: Returns the square of a number.(取给定值的平方) 
所属单元: System 
定义: function Sqr(X: Extended): Extended; 
详细解释: 



The Sqr function returns the square of the argument.

X is a floating-point expression. The result, of the same type as X, is the square of X, or X*X.
(Sqr返回X得平方值,X是一个浮点型的数,返回值的类型与X 相同,值为X*X)
 
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; 
返回
 
函数名 sqrt 
简要介绍: Returns the square root of X. 
所属单元: System 
定义: function Sqrt(X: Extended): Extended; 
详细解释: 



X is a floating-point expression. The result is the square root of X.
(取X的平方根,X是一个浮点数,返回值也是个浮点数)
 
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;
 
返回
 
函数名 Trunc 
简要介绍: Truncates a real number to an integer.(截取一个实数的整数部分) 
所属单元: System 
定义: function Trunc(X: Extended): Int64; 
详细解释: 



The Trunc function truncates a real-type value to an integer-type value. X is a real-type expression. Trunc returns an Int64 value that is the value of X rounded toward zero.

If the truncated value of X is not within the Int64 range, an EInvalidOp exception is raised.
 
范例: var
S, T: string;
begin
Str(1.4:2:1, T);
S := T + ' Truncs to ' + IntToStr(Trunc(1.4)) + #13#10;
Str(1.5:2:1, T);
S := S + T + ' Truncs to ' + IntToStr(Trunc(1.5)) + #13#10;
Str(-1.4:2:1, T);
S := S + T + ' Truncs to ' + IntToStr(Trunc(-1.4)) + #13#10;
Str(-1.5:2:1, T);
S := S + T + ' Truncs to ' + IntToStr(Trunc(-1.5));
MessageDlg(S, mtInformation, [mbOk], 0);
end; 

                                

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