Delphi中的算术运算函数
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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)
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)
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;
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)
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
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)。
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;
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:
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。)
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。)
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。)
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.)
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])
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.)
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;
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;
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;
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;