frequency

I am trying to perform FFT on an audio file to find frequency using the Accelerate framework. I have adapted code (probably wrong) from this question: Spectrogram from AVAudioPCMBuffer using Accelerate framework in Swift Although, the magnitudes from ' spectrum ' are either ' 0 ', ' inf ' or ' nan ', and the ' real ' and ' imag ' components of the complex split print similar results; indicating that this is the cause of the problem as: ' magnitude = sqrt(pow( real ,2)+pow( imag ,2) '. Correct me if i'm wrong, but I think the rest of the code is ok. Why am I receiving these results and how can

So I found this Google interview algorithm question online. It's really interesting and I still have not come up with a good solution yet. Please have a look, and give me a hint/solution, it would be great if you can write the code in Java :). "Design an algorithm that, given a list of n elements in an array, finds all the elements that appear more than n/3 times in the list. The algorithm should run in linear time. (n >=0 ) You are expected to use comparisons and achieve linear time. No hashing/excessive space/ and don't use standard linear time deterministic selection algo" My solution was

My question involves writing code using the dplyr package in R I have a relatively large dataframe (approx 5 million rows) with 2 columns: the first with an individual identifier ( id ), and a second with a date ( date ). At present, each row indicates the occurrence of an action (taken by the individual in the id column) on the date in the date column. There are about 300,000 unique individuals, and about 2600 unique dates. For example, the beginning of the data look like this: id date John12 2006-08-03 Tom2993 2008-10-11 Lisa825 2009-07-03 Tom2993 2008-06-12 Andrew13 2007-09-11 I'd like to

I need to develop a java program that asks the user to enter some integers and find the largest, and smallest number, and the average of those numbers. Then, divides the set of array into a number of sub-intervals that the user specifies, then it generates a boundary points each has a length of sub-interval width.. The problem is that I need to create a frequency: ex: Interval: 14.5-16.5 Frequency: 1 (here it should shows how many integers belong to this boundaries) Interval: 16.5-18.5 Frequency: 4 and so on. Here is the code I have so far, almost done except finding the frequency of each

I have a while True loop which sends variables to an external function, and then uses the returned values. This send/receive process has a user-configurable frequency, which is saved and read from an external .ini configuration file. I've tried time.sleep(1 / Frequency), but am not satisfied with the accuracy, given the number of threads being used elsewhere. E.g. a frequency of 60Hz (period of 0.0166667) is giving an 'actual' time.sleep() period of ~0.0311. My preference would be to use an additional while loop, which compares the current time to the start time plus the period, as follows:

I got an array of data voltages and I want to get the RMS value from the FFT that has been applied before to that data. I've seen that RMS in time domain should be equal to RMS(fft) / sqrt(nFFT) from Parseval's Theorem, but gives me different results. I'm using these functions: 1)FFT public static VectorDPoint FFT(double[] trama, double samplingFreq) { double fs = samplingFreq; // Sampling frequency double t1 = 1 / fs; // Sample time int l = trama.Length; // Length of signal // Time vector //Vector t = Normal(0, l, 1) * t1; //// Values vector //Vector y = new Vector(trama); // We just use half