Chris@25: # jsfft
Chris@25: 
Chris@25: Small, efficient Javascript FFT implementation for node or the browser.
Chris@25: 
Chris@25: ## Usage
Chris@25: 
Chris@25: JSFFT ships with a **complex_array** and a **fft** module.
Chris@25: 
Chris@25: ```javascript
Chris@25: var data = new complex_array.ComplexArray(512)
Chris@25: // Use the in-place mapper to populate the data.
Chris@25: data.map(function(value, i, n) {
Chris@25:   value.real = (i > n/3 && i < 2*n/3) ? 1 : 0
Chris@25: })
Chris@25: ```
Chris@25: 
Chris@25: Including the **fft** module attaches FFT methods to ComplexArray.  FFT and
Chris@25: InvFFT perform in-place transforms on the underlying data:
Chris@25: 
Chris@25: ```javascript
Chris@25: var frequencies = data.FFT()
Chris@25: // Implement a low-pass filter using the in-place mapper.
Chris@25: frequencies.map(function(frequency, i, n) {
Chris@25:   if (i > n/5 && i < 4*n/5) {
Chris@25:     frequency.real = 0
Chris@25:     frequency.imag = 0
Chris@25:   }
Chris@25: })
Chris@25: ```
Chris@25: 
Chris@25: Alternatively, frequency-space filters can be implemented via the frequencyMap:
Chris@25: 
Chris@25: ```javascript
Chris@25: var filtered = data.frequencyMap(function(frequency, i, n) {
Chris@25:   if (i > n/5 && i < 4*n/5) {
Chris@25:     frequency.real = 0
Chris@25:     frequency.imag = 0
Chris@25:   }
Chris@25: })
Chris@25: ```
Chris@25: 
Chris@25: ## Other Implementations
Chris@25: 
Chris@25: [DSP](https://github.com/corbanbrook/dsp.js) is a full featured Digital Signal
Chris@25: Processing library in JS which includes a JS FFT implementation.