Length 指令

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范例：

Length( <向量> ) 产生此 <向量> 的长度。
Length( <點> ) 产生此 <点> 的位置向量长度。
Length( <串列> ) 产生此 <串列> 的长度，亦即此 <串列> 中元素的个数。
Length( <文字> ) 产生此 <文字> 的字元个数（译注：不论全半形）。
Length( <軌跡> ) 回传组成此 <轨迹> 的点个数。若要取得轨迹本身的长度，可使用 Perimeter_指令。returns the number of points that the given locus is made up of. Use Perimeter(Locus) to get the length of the locus itself. For details see the article about First Command.
Length( <圓弧> ) returns the arc length (i.e. just the length of the curved section) of an arc or sector.

Length( <Function>, <Start x-Value>, <End x-Value> ): Yields the length of the function graph in the given interval.; 范例： Length(2x, 0, 1) returns 2.236067977, about \sqrt{5}.
Length( <Function>, <Start Point>, <End Point> ): Yields the length of the function graph between the two points.; 备注： If the given points do not lie on the function graph, their x‐coordinates are used to determine the interval.
Length( <Curve>, <Start t-Value>, <End t-Value> ): Yields the length of the curve between the two values of the parameter.
Length( <Curve>, <Start Point>, <End Point> ): Yields the length of the curve between the two points that lie on the curve.

CAS Syntax

Length( <Function>, <Start x-Value>, <End x-Value> ): Calculates the length of a function graph between the two points.; 范例： Length(2 x, 0, 1) yields \sqrt{5}.
Length( <Function>, <Variable>, <Start x-Value>, <End x-Value> ): Calculates the length of a function graph from Start Point to End Point.; 范例： Length(2 a, a, 0, 1) yields \sqrt{5}.

备注： See also