From a532068fbce001094061d0dd00b03dc995641a6c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9r=C3=B4me?= <jerome.tabeaud@gmail.com>
Date: Sun, 17 Nov 2019 17:52:42 +0100
Subject: [PATCH] Added filtered uniform noise demo in main.cpp.

---
 main.cpp | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/main.cpp b/main.cpp
index 4ca436c..3f56158 100644
--- a/main.cpp
+++ b/main.cpp
@@ -1,3 +1,4 @@
+#include <fstream>
 #include <iostream>
 
 #include "utils.hpp"
@@ -13,7 +14,8 @@ int main()
 {
 	cout.precision(16);
 
-	{
+	if(0)
+	{// step response of simple 1st order filter
 		double	tend = 10.,
 				dt = 0.1,
 				t, y = 0.;
@@ -27,5 +29,35 @@ int main()
 		}
 	}
 
+	// if(0)
+	{// Generate some uniform noise and filter it to see if the filter class works as expected
+		uint32_t state[5] = {123456, 654897, 812656, 87913951, 0};
+
+		double	tend = 10.,
+				dt = 0.025,
+				omega = 2*M_PI*10,
+				Q = 20.,
+				t, y = 0., y2;
+		FlyByWire::Filter2 filt1 = FlyByWire::Filter2::Bandpass(omega, Q, dt);
+
+		std::ofstream out("data_out.m", std::ios_base::out | std::ios_base::trunc);
+
+		if(!out.is_open())
+		{
+			std::cerr << "Could not open the file in writing mode.\n";
+			return 1;
+		}
+
+		out << "a = [";
+		for(int i = 0 ; i <= (tend/dt) ; i++)
+		{
+			t = i*dt;
+			y = RAND_XORWOW_A_B(state, -1., 1.);
+			y2 = filt1.Filter(y);
+			out << t << " " << y << " " << y2 << "\n";
+		}
+		out << "];\nplot(a(:,1), a(:,2), a(:,1), a(:,3), 'linewidth', 2.), grid on, legend('original', 'filtered')";
+	}
+
 	return 0;
 }