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DCT Detrending (Convenience Function)

Source: R/RcppExports.R
detrend_dct_cpp.Rd

Removes low-frequency components using discrete cosine transform.

Usage

detrend_dct_cpp(data, n_basis = 4L)

Arguments

data

Numeric matrix with voxels as rows and timepoints as columns

n_basis

Number of DCT basis functions to remove (including constant). Default 4 removes constant, linear, and first two cosine harmonics.

Value

Numeric matrix with low-frequency components removed

Details

DCT detrending is commonly used in fMRI preprocessing. The number of basis functions controls the high-pass filter cutoff:

  • n_basis = 1: mean removal only

  • n_basis = 2: ~ linear detrend

  • n_basis = 4-6: typical for fMRI (removes drift < ~0.01 Hz for TR=2s)

Higher n_basis = more aggressive high-pass filtering.