LPF: add sample frequency getter

src/lib/mathlib/math/filter/LowPassFilter2pVector3f.cpp

@@ -43,6 +43,7 @@ namespace math
 void LowPassFilter2pVector3f::set_cutoff_frequency(float sample_freq, float cutoff_freq)
 {
 	_cutoff_freq = cutoff_freq;
+	_sample_freq = sample_freq;
 
 	// reset delay elements on filter change
 	_delay_element_1.zero();

src/lib/mathlib/math/filter/LowPassFilter2pVector3f.hpp

@@ -74,12 +74,16 @@ public:
 	// Return the cutoff frequency
 	float get_cutoff_freq() const { return _cutoff_freq; }
 
+	// Return the sample frequency
+	float get_sample_freq() const { return _sample_freq; }
+
 	// Reset the filter state to this value
 	matrix::Vector3f reset(const matrix::Vector3f &sample);
 
 private:
 
 	float _cutoff_freq{0.0f};
+	float _sample_freq{0.0f};
 
 	float _a1{0.0f};
 	float _a2{0.0f};