April 2014
Beginner to intermediate
830 pages
15h 21m
Chinese
Content preview from Mathematica 錦囊妙計
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40
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第二章
接下來，我將應用這個技巧兩次，表列出前 12 個正多邊形，並且於圖形中央印出其邊
數與內角值。[Page-039]
首先是使用
Table
指令產生角度的陣列，這是程式碼最深層的部分，它包含
n
個圓周上
平均分布的圓周角，其中
n
從 3 依序增加至 14。以下以表格方式列出
angles
的內容。
如前文所述，一旦我們已有此串列，直接使用
Map
指令運算是較好的方法。
ch02.indd 40 2014/4/2 上午 03:32:04
2.4 於單次運算中映射數個函數
|
41
Polygon
繪圖物件需使用座標串列，因此需使用
Sin
與
Cos
映射至
angle
的第二層，將
圓周角轉換為座標。為節省空間，以下僅列出前三個結果。[Page-040]
接著使用相同技巧，同時建立多邊形與字串的插入；
Partition
與
GraphicsGrid
只用來
排列圖形。
延伸資訊
訣竅 2.5 中討論
MapIndexed
映射指令，這是
Map
指令的變形，它會將元素於串列中的位
置索引值（index）作為函數的第 2 個引數。
ch02.indd 41 2014/4/2 上午 03:32:05
42
|
第二章
2.5 於映射指令中加入元素索引值（Index）
問題點
與
Map
指令相同地，你想將函數映射至串列中，但此函數除了元素值之外
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