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-arduinoFFT
-==========
-
-# Fast Fourier Transform for Arduino
-
-This is a fork from https://code.google.com/p/makefurt/ which has been abandoned since 2011.
-~~This is a C++ library for Arduino for computing FFT.~~ Now it works both on Arduino and C projects. This is version 2.0 of the library, which has a different [API](#api). See here [how to migrate from 1.x to 2.x](#migrating-from-1x-to-2x).
-Tested on Arduino 1.6.11 and 1.8.10.
-
-## Installation on Arduino
-
-Use the Arduino Library Manager to install and keep it updated. Just look for arduinoFFT. Only for Arduino 1.5+
-
-## Manual installation on Arduino
-
-To install this library, just place this entire folder as a subfolder in your Arduino installation. When installed, this library should look like:
-
-`Arduino\libraries\arduinoFTT` (this library's folder)
-`Arduino\libraries\arduinoFTT\src\arduinoFTT.h` (the library header file. include this in your project)
-`Arduino\libraries\arduinoFTT\keywords.txt` (the syntax coloring file)
-`Arduino\libraries\arduinoFTT\Examples` (the examples in the "open" menu)
-`Arduino\libraries\arduinoFTT\LICENSE` (GPL license file)
-`Arduino\libraries\arduinoFTT\README.md` (this file)
-
-## Building on Arduino
-
-After this library is installed, you just have to start the Arduino application.
-You may see a few warning messages as it's built.
-To use this library in a sketch, go to the Sketch | Import Library menu and
-select arduinoFTT. This will add a corresponding line to the top of your sketch:
-
-`#include <arduinoFTT.h>`
-
-## API
-
-* ```ArduinoFFT(T *vReal, T *vImag, uint_fast16_t samples, T samplingFrequency, T * weighingFactors = nullptr);```
-Constructor.
-The type `T` can be `float` or `double`. `vReal` and `vImag` are pointers to arrays of real and imaginary data and have to be allocated outside of ArduinoFFT. `samples` is the number of samples in `vReal` and `vImag` and `weighingFactors` (if specified). `samplingFrequency` is the sample frequency of the data. `weighingFactors` can optionally be specified to cache weighing factors for the windowing function. This speeds up repeated calls to **windowing()** significantly. You can deallocate `vReal` and `vImag` after you are done using the library, or only use specific library functions that only need one of those arrays.
-
-```C++
-const uint32_t nrOfSamples = 1024;
-auto real = new float[nrOfSamples];
-auto imag = new float[nrOfSamples];
-auto fft = ArduinoFFT<float>(real, imag, nrOfSamples, 10000);
-// ... fill real + imag and use it ...
-fft.compute();
-fft.complexToMagnitude();
-delete [] imag;
-// ... continue using real and only functions that use real ...
-auto peak = fft.majorPeak();
-```
-* ```~ArduinoFFT()```
-Destructor.
-* ```void complexToMagnitude() const;```
-Convert complex values to their magnitude and store in vReal. Uses vReal and vImag.
-* ```void compute(FFTDirection dir) const;```
-Calcuates the Fast Fourier Transform. Uses vReal and vImag.
-* ```void dcRemoval() const;```
-Removes the DC component from the sample data. Uses vReal.
-* ```T majorPeak() const;```
-Returns the frequency of the biggest spike in the analyzed signal. Uses vReal.
-* ```void majorPeak(T &frequency, T &value) const;```
-Returns the frequency and the value of the biggest spike in the analyzed signal. Uses vReal.
-* ```uint8_t revision() const;```
-Returns the library revision.
-* ```void setArrays(T *vReal, T *vImag);```
-Replace the data array pointers.
-* ```void windowing(FFTWindow windowType, FFTDirection dir, bool withCompensation = false);```
-Performs a windowing function on the values array. Uses vReal. The possible windowing options are:
- * Rectangle
- * Hamming
- * Hann
- * Triangle
- * Nuttall
- * Blackman
- * Blackman_Nuttall
- * Blackman_Harris
- * Flat_top
- * Welch
-
- If `withCompensation` == true, the following compensation factors are used:
- * Rectangle: 1.0 * 2.0
- * Hamming: 1.8549343278 * 2.0
- * Hann: 1.8554726898 * 2.0
- * Triangle: 2.0039186079 * 2.0
- * Nuttall: 2.8163172034 * 2.0
- * Blackman: 2.3673474360 * 2.0
- * Blackman Nuttall: 2.7557840395 * 2.0
- * Blackman Harris: 2.7929062517 * 2.0
- * Flat top: 3.5659039231 * 2.0
- * Welch: 1.5029392863 * 2.0
-
-## Special flags
-
-You can define these before including arduinoFFT.h:
-
-* #define FFT_SPEED_OVER_PRECISION
-Define this to use reciprocal multiplication for division and some more speedups that might decrease precision.
-
-* #define FFT_SQRT_APPROXIMATION
-Define this to use a low-precision square root approximation instead of the regular sqrt() call. This might only work for specific use cases, but is significantly faster. Only works if `T == float`.
-
-See the `FFT_speedup.ino` example in `Examples/FFT_speedup/FFT_speedup.ino`.
-
-# Migrating from 1.x to 2.x
-
-* The function signatures where you could pass in pointers were deprecated and have been removed. Pass in pointers to your real / imaginary array in the ArduinoFFT() constructor. If you have the need to replace those pointers during usage of the library (e.g. to free memory) you can do the following:
-
-```C++
-const uint32_t nrOfSamples = 1024;
-auto real = new float[nrOfSamples];
-auto imag = new float[nrOfSamples];
-auto fft = ArduinoFFT<float>(real, imag, nrOfSamples, 10000);
-// ... fill real + imag and use it ...
-fft.compute();
-fft.complexToMagnitude();
-delete [] real;
-// ... replace vReal in library with imag ...
-fft.setArrays(imag, nullptr);
-// ... keep doing whatever ...
-```
-* All function names are camelCase case now (start with lower-case character), e.g. "windowing()" instead of "Windowing()".
-
-## TODO
-* Ratio table for windowing function.
-* Document windowing functions advantages and disadvantages.
-* Optimize usage and arguments.
-* Add new windowing functions.
-* ~~Spectrum table?~~