Creates a polynomial basis matrix for detrending.
Usage
make_poly_basis(n_time, degree)
Arguments
- n_time
Number of timepoints
- degree
Polynomial degree (0 = constant, 1 = linear, 2 = quadratic, etc.)
Value
Numeric matrix (n_time x (degree+1)) with orthonormalized polynomial basis
Details
Uses Gram-Schmidt orthonormalization for numerical stability.
Degree 0 = mean removal, 1 = linear detrend, 2 = quadratic, etc.