Generate the `n`×`n` discrete cosine transform matrix. The optional second
与 .wl 参考的差异： `FourierDCTMatrix` for n ≥ 5
FourierDCTMatrix[n]
FourierDCTMatrix[n, m]
FourierDCTMatrix[1]
→ {{1}}FourierDCTMatrix[3]
→ {{1/Sqrt[3], 1/2, 1/(2*Sqrt[3])}, {1/Sqrt[3], 0, -(1/Sqrt[3])}, {1/Sqrt[3], -1/2, 1/(2*Sqrt[3])}}FourierDCTMatrix[3, 1]
→ {{1/2, 1/2, 1/2}, {1, 0, -1}, {1/2, -1/2, 1/2}}FourierDCTMatrix[3, 3]
→ {{1/Sqrt[3], 1/Sqrt[3], 1/Sqrt[3]}, {1, 0, -1}, {1/Sqrt[3], -2/Sqrt[3], 1/Sqrt[3]}}