Problem 930. 1D DCT-II transform.

Created by Ryszard Maciol

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Implement a function that calculates 1D Discrete Cosine Transform (DCT-II) for each row of a given input matrix so that the outputs are in columns.

For example:

Input:

[1 0 0 0]

Gives:

mydct([1 0 0 0])
ans =
          0.5
      0.65328
          0.5
       0.2706

Solve

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Last Solution submitted on Jan 20, 2026

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1 Comment

Rafael S.T. Vieira on 22 Oct 2020

A fair warning to the challenger: the requested DCT-II is the orthogonal version, which means it needs to be multiplied by sqrt(2/N) where N is the size of the row, and the first element of the DCT x0 needs to be multiplied by 1/sqrt(2). It took me a while to understand. Wikipedia's formula is almost right, but it is missing those terms, which are mentioned only further below. Look at MATLAB's documentation (DCT-2), https://www.mathworks.com/help/signal/ref/dct.html, to find the proper formula.

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Problem 930. 1D DCT-II transform.

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Problem 930. 1D DCT-II transform.

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Problem Recent Solvers21

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