// dft evaluates a series of [lintrans.LinearTransformation] sequentially on the ctIn and stores the result in opOut.
func (eval *Evaluator) dft(ctIn *rlwe.Ciphertext, matrices []ltcommon.LinearTransformation, opOut *rlwe.Ciphertext) (err error) {

	inputLogSlots := ctIn.LogDimensions

	// Sequentially multiplies w with the provided dft matrices.
	if err = eval.LTEvaluator.EvaluateSequential(ctIn, matrices, opOut); err != nil {
		return
	}

	// Encoding matrices are a special case of `fractal` linear transform
	// that doesn't change the underlying plaintext polynomial Y = X^{N/n}
	// of the input ciphertext.
	opOut.LogDimensions = inputLogSlots

	return
}