pub fn toeplitz_matvec<T: Float>(kernel: &[T], x: &[T]) -> Vec<T>Expand description
Causal Toeplitz matrix-vector product — the convolutional view of an
SSM. Implicitly applies the lower-triangular matrix
M[i][j] = kernel[i - j] for j <= i, 0 otherwise
to x, i.e. computes the causal convolution:
y[i] = sum_{j=0}^{i} kernel[i - j] * x[j]
kernel and x must be the same length n; cost is O(n^2). This is
the direct reference implementation — fft_conv computes the exact
same quantity in O(n log n) and is tested against this function.