Task: dct_type_I_scipy_fftpack

Concise description:
This task involves computing the Discrete Cosine Transform (DCT) Type I of a set of numbers arranged in a grid.  
In DCT Type I, the data is assumed to be even-symmetric at the boundaries, meaning the values mirror at the edges.  
This symmetry requires the grid to have one extra row and column compared to the logical size.  
The output is a two-dimensional array (of size (n+1)×(n+1)) where each element represents a cosine frequency coefficient.  
The output grid captures the frequency content of the original data through these coefficients.

Input:
A real-valued (n+1)×(n+1) array represented as a list of n+1 lists of numbers.

Example input:
[[0.2, 0.5, 0.7],
 [0.3, 0.8, 0.6],
 [0.9, 0.4, 0.1]]

Output:
A (n+1)×(n+1) array of real numbers indicating the cosine frequency coefficients.

Example output:
[[...], [...], [...]]

Category: signal_processing