然而当一个信号经过了处理之后，它仍不得不被重新变换回它原始的形式。

After a signal has been processed, however, it has to be converted back into its original form.

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最常见的数字信号处理技术之一是离散傅立叶变换（DFT），它把一个信号分解成它的组成频率，并表示成一个矩阵。

One of the most common digital-signal-processing techniques is the discrete Fourier transform (DFT), which breaks a signal into its component frequencies and can be represented as a matrix.

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那是傅里叶变换美妙的部分，但对于某些信号处理应用来说，带状矩阵可以比傅里叶变换更加高效。

That's part of what makes Fourier wonderful. "Nonetheless, for some signal-processing applications, banded matrices could prove more efficient than the Fourier transform."

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