範例：立方雲規線內插

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範例：立方雲規線內插

使用 lspline、pspline 及 cspline 函數建構立方雲規線 (分段多項式)，並在數據點之間進行內插。

1. 定義矩陣。

2. 使用 csort 函數排序數據，讓 Cu 的第二欄以遞升排序。

提供給雲規線函數的 x 值必須以遞升排序。

3. 建立含有 x 與 y 數據的向量。

4. 使用 cspline 函數建立立方雲規線向量，然後使用 interp 函數取得內插值。

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5. 使用 lspline 函數建立線性雲規線向量，然後使用 interp 函數取得內插值。

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6. 使用 pspline 函數建立拋物線雲規線向量，然後使用 interp 函數取得內插值。

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7. 繪製原始數據點與立方雲規線。

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8. 放大前兩個數據點。

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三個雲規線函數會產生相等的結果，但在端點處的結果除外。

9. 計算內插線性雲規線向量的第二個導數，並顯示其在端點處等於 0。