I can't identify the input data

fft_input[i] = k; // put real data into even bins fft_input[i+1] = 0; // set odd bins to 0

/*fft_adc.pdeguest openmusiclabs.com 8.18.12example sketch for testing the fft library.it takes in data on ADC0 (Analog0) and processes themwith the fft. the data is sent out over the serialport at 115.2kb. there is a pure data patch forvisualizing the data.*/#define LOG_OUT 1 // use the log output function#define FFT_N 256 // set to 256 point fft#include <FFT.h> // include the libraryvoid setup() { Serial.begin(9600); // use the serial port TIMSK0 = 0; // turn off timer0 for lower jitter ADCSRA = 0xe5; // set the adc to free running mode ADMUX = 0x40; // use adc0 DIDR0 = 0x01; // turn off the digital input for adc0}void loop() { while(1) { // reduces jitter cli(); // UDRE interrupt slows this way down on arduino1.0 for (int i = 0 ; i < 512 ; i += 2) { // save 256 samples while(!(ADCSRA & 0x10)); // wait for adc to be ready ADCSRA = 0xf5; // restart adc byte m = ADCL; // fetch adc data byte j = ADCH; int k = (j << 8) | m; // form into an int k -= 0x0200; // form into a signed int k <<= 6; // form into a 16b signed int fft_input[i] = k; // put real data into even bins fft_input[i+1] = 0; // set odd bins to 0 //Serial.println(k); }// // for(int i=0;i<512;i += 2)// {// fft_input[i] = sin(i/(2*3.14*30));// fft_input[i+1] = 0;// } fft_window(); // window the data for better frequency response fft_reorder(); // reorder the data before doing the fft fft_run(); // process the data in the fft fft_mag_log(); // take the output of the fft sei(); for (uint8_t j = 0; j < FFT_N/8; j++) { Serial.print(j); Serial.print(" "); } Serial.println(""); for (uint8_t j=0; j<FFT_N/8; j++){ Serial.print(fft_log_out[j]); Serial.print(" "); } Serial.println(" "); Serial.println(); }}

For 1/8th of bins, what do I change 512 to

well 64 might be good don't you think?

/*fft_adc.pdeguest openmusiclabs.com 8.18.12example sketch for testing the fft library.it takes in data on ADC0 (Analog0) and processes themwith the fft. the data is sent out over the serialport at 115.2kb. there is a pure data patch forvisualizing the data.*/#define LOG_OUT 1 // use the log output function#define FFT_N 64 // set to 256 point fft......... for (int i = 0 ; i < 128 ; i += 2) ..........