func cVeryclose(a, b complex128) bool          { return cTolerance(a, b, 4e-16) }
func cAlike(a, b complex128) bool {
	var realAlike, imagAlike bool
	if isExact(real(b)) {
		realAlike = alike(real(a), real(b))
	} else {
		// Allow non-exact special cases to have errors in ULP.
		realAlike = veryclose(real(a), real(b))
	}
	if isExact(imag(b)) {
		imagAlike = alike(imag(a), imag(b))
	} else {