[AUD-010][High] Make FrequencyResponse::Calculate reusable

[gabrielsantosphilips]

Audit finding

• ID: AUD-010
• Status: Verified defect
• Severity: High
• Confidence: High
• Audited revision: 2f479320d805a1f9f35ebe4afaaeeded48913a94

Problem

FrequencyResponse::Calculate() appends to three bounded member vectors without clearing or overwriting them. The public object appears reusable, but a second call exceeds capacity and aborts.

Source:

numerical-toolbox-cpp/numerical/control_analysis/FrequencyResponse.hpp

Lines 51 to 83 in 2f47932

	FrequencyResponse<T, NumberOfPoints>::Calculate()
	{
	const auto maxSize = static_cast<T>(response.max_size());
	const auto fstart = sampleFrequency / maxSize;
	const auto fend = sampleFrequency / static_cast<T>(2);
	const auto multiplier = static_cast<T>(math::Pow(static_cast<double>(fend / fstart), 1.0 / (static_cast<double>(maxSize) - 1.0)));
	for (std::size_t n = 0; n < response.max_size(); ++n)
	{
	auto f = fstart * static_cast<T>(math::Pow(static_cast<double>(multiplier), static_cast<double>(n)));
	auto omega = static_cast<T>(2) * static_cast<T>(std::numbers::pi) * f / sampleFrequency;
	std::complex<T> numerator(static_cast<T>(0), static_cast<T>(0));
	std::complex<T> denominator(static_cast<T>(0), static_cast<T>(0));
	for (std::size_t i = 0; i < b.size(); ++i)
	numerator += b[i] * std::polar(static_cast<T>(1), -omega * static_cast<T>(i));
	for (std::size_t i = 0; i < a.size(); ++i)
	denominator += a[i] * std::polar(static_cast<T>(1), -omega * static_cast<T>(i));
	if (denominator == static_cast<T>(0))
	denominator.real(static_cast<T>(1));
	auto h = numerator / denominator;
	auto magnitude = std::max(std::abs(h), std::numeric_limits<T>::min());
	frequencies.emplace_back(f);
	response.emplace_back(static_cast<T>(20) * math::Log10(magnitude));
	phase.emplace_back(std::arg(h) * static_cast<T>(180) / static_cast<T>(std::numbers::pi));
	}
	return std::make_tuple(frequencies, response, phase);

Reproduction

Construct FrequencyResponse<float, 8> with numerator/denominator {1} and call Calculate() twice. The second call asserts in BoundedVector::emplace_back. Current determinism coverage compares two fresh objects instead.

Acceptance criteria

• Clear or overwrite all result buffers at the start of each calculation.
• Repeated calls return identical vectors and sizes.
• Add same-object repeat tests using TEST_F on float.