Test 3 Problem FFT
Pressure data relative to background pressure is taken every quarter second for 16 seconds producing 64 data points corresponding to times between 0 seconds and 15.75 seconds
It is suspected that periodic phenomena are contributing to variations in this pressure.
Identify any important sine or cosine terms contributing to this variation and their frequencies and periods and amplitudes.
Then graph the linear combination of the most important terms, superimposed on a graph of the data.
Take the difference between this function at these 64 times and the data creating a residual data vector. Test this vector for normality.
y=[ -9.4373 3.2161 5.2967 2.9761 -6.8430 -0.0374 7.2257 15.8328 9.1546 -7.3490 -2.9913 -19.0965 -9.4340 -3.7345 2.4749 -6.3982 -7.9712 7.3415 8.4246 7.1256 -0.3645 -11.2210 -17.3242 -12.9688 -4.1622 10.7102 -4.2850 -3.1927 -1.9358 14.6487 14.1757 11.2624 -2.4246 -9.3811 -5.9873 -8.0098 2.5665 -0.6184 1.8448 -1.8676 2.8954 17.1060 4.4648 -4.5872 -19.5737 -9.5261 -6.2455 0.5116 2.4759 -3.6573 -3.2943 2.4109 20.8644 18.5943 2.2224 -10.2019 -16.7347 -8.9398 6.7998 1.2489 2.1519 -4.4203 -2.5412 13.4601]