vec spectrum(const vec &v, const vec &w, int noverlap)
{
int nfft = w.size();
it_assert_debug(pow2i(levels2bits(nfft)) == nfft,
"The window size must be a power of two in spectrum()!");
vec P(nfft / 2 + 1), wd(nfft);
P = 0.0;
double w_energy = energy(w);
if (nfft > v.size()) {
P = sqr(abs(fft(to_cvec(elem_mult(zero_pad(v, nfft), w)))(0, nfft / 2)));
P /= w_energy;
}
else {
int k = (v.size() - noverlap) / (nfft - noverlap), idx = 0;
for (int i = 0; i < k; i++) {
wd = elem_mult(v(idx, idx + nfft - 1), w);
P += sqr(abs(fft(to_cvec(wd))(0, nfft / 2)));
idx += nfft - noverlap;
}
P /= k * w_energy;
}
P.set_size(nfft / 2 + 1, true);
return P;
}
flt_dbl calc_euclidian_distance( sparse_flt_dbl_vec & datapoint, sparse_flt_dbl_vec &cluster, flt_dbl sqr_sum, flt_dbl sqr_sum0){
//sparse_flt_dbl_vec diff = minus(datapoint , cluster);
//return sqrt(sum_sqr(diff));
sparse_flt_dbl_vec mult = elem_mult(datapoint, cluster);
flt_dbl diff = (sqr_sum + sqr_sum0 - 2*sum(mult));
return sqrt(fabs(diff)); //because of numerical errors, diff may be negative
}
cvec polyval(const cvec &p, const cvec &x)
{
it_error_if(p.size() == 0, "polyval: size of polynomial is zero");
it_error_if(x.size() == 0, "polyval: size of input value vector is zero");
cvec out(x.size());
out = p(0);
for (int i = 1; i < p.size(); i++)
out = p(i) + elem_mult(x, out);
return out;
}
cvec polyval(const cvec &p, const vec &x)
{
it_error_if(p.size() == 0, "polyval: size of polynomial is zero");
it_error_if(x.size() == 0, "polyval: size of input value vector is zero");
cvec out(x.size());
out = p(0);
for (int i = 1; i < p.size(); i++)
out = std::complex<double>(p(i)) + elem_mult(to_cvec(x), out);
return out;
}
void BERC::estimate_delay(const bvec &in1, const bvec &in2, int mindelay,
int maxdelay)
{
int num, start1, start2;
int min_input_length = std::min(in1.length(), in2.length());
int bestdelay = mindelay;
double correlation;
double bestcorr = 0;
for (int i = mindelay; i < maxdelay; i++) {
num = min_input_length - std::abs(i) - ignorefirst - ignorelast;
start1 = (i < 0) ? -i : 0;
start2 = (i > 0) ? i : 0;
correlation = fabs(sum(to_vec(elem_mult(in1.mid(start1, num),
in2.mid(start2, num)))));
if (correlation > bestcorr) {
bestdelay = i;
bestcorr = correlation;
}
}
delay = bestdelay;
}
QuantumStateITPP evolve_with_phases(QuantumStateITPP &psi, itpp::Vec<double> eigenvalues, double t){
// psi=exp(-I*time*eigenvalues) * psi_0
QuantumStateITPP tmp;
tmp.coefficients = elem_mult(itpp::exp(eigenvalues * t * std::complex<double>(0.,1.)),psi.coefficients) ;
return tmp;
}
int main(int argc, char *argv[])
{
int i,j,k; //Counter variable
bvec b_source_bits, b_decoded_bits, b_encoded_bits;
ivec i_decoded_bits, i_decoded_symbols;
cvec c_received_signals;
vec d_received_llr;
ivec No_of_Errors, No_of_Bits, No_of_BlockErrors, No_of_Blocks;
//Channel setup
cvec channel_gains;
TDL_Channel ray_channel; // default: uncorrelated Rayleigh fading channel
AWGN_Channel awgn_channel; // AWGN channel
//-------------------------------------------------------CONV
//Convolutional codes module, CONV
CONV conv;
char *ctrlfile;
if(argc==1) ctrlfile = "control.conv.par";
else ctrlfile = argv[1];
conv.set_parameters_from_file(ctrlfile);
conv.initialise();
//result file
FILE *f; char *resultfile= conv.get_result_filename();
f=fopen(resultfile, "w");
//print out parameters
conv.print_parameters(stdout);
conv.print_parameters(f);
//-------------------------------------------------------CONV
// read simulation parameters
FILE *sim_file;
FILESERVICE fileser;
sim_file = fopen("control.sim.par", "r");
if(sim_file==NULL) it_error("control.sim.par not found");
int max_nrof_frame = fileser.scan_integer(sim_file);
double SNR_start = fileser.scan_double(sim_file);
double SNR_step = fileser.scan_double(sim_file);
double SNR_end = fileser.scan_double(sim_file);
double G_sd = fileser.scan_double(sim_file);
double G_sr = fileser.scan_double(sim_file);
double G_rd = fileser.scan_double(sim_file);
int channel_type = fileser.scan_integer(sim_file);
int mapper_bps = fileser.scan_integer(sim_file);
fclose(sim_file);
char text[100];
sprintf( text, "%f:%f:%f", SNR_start, SNR_step, SNR_end );
//SNR setup
vec SNRdB = text; //Setting the simulation Eb/N0 range in dB
int M = 1<<mapper_bps;
PSK psk(M);
cvec source_frame;
double rate = (double)mapper_bps * conv.get_rate();
printf ( "! %d-PSK (mapper_bps=%d) :: Overall_Rate=%.4f\n!\n", M, mapper_bps, rate);
fprintf(f,"! %d-PSK (mapper_bps=%d) :: Overall_Rate=%.4f\n!\n", M, mapper_bps, rate);
vec SNR = pow(10.0, SNRdB/10.0);
vec N0 = 1.0/SNR;
vec sigma2 = N0/2;
BERC berc; //BER counter
BLERC blerc; //FER counter
Real_Timer tt; //Time counter
vec ber(SNRdB.length()); //allocate memory for vector to store BER
vec bler(SNRdB.length()); //allocate memory for vector to store FER
ber.clear(); //Clear up buffer of BER counter
bler.clear(); //Clear up buffer of FER counter
blerc.set_blocksize((long)conv.get_info_bit_length()); //set blocksize of the FER counter
tt.tic(); //Start timer
//RNG_randomize(); //construct random source
RNG_reset(0); //reset random seed
b_source_bits.set_size(conv.get_info_bit_length(), false);
b_encoded_bits.set_size(conv.get_coded_bit_length(), false);
c_received_signals.set_size(conv.get_sym_length(), false);
d_received_llr.set_size(conv.get_coded_bit_length(), false);
b_decoded_bits.set_size(conv.get_info_bit_length(), false);
No_of_Errors.set_size(SNRdB.length(), false); //Set the length
No_of_Bits.set_size(SNRdB.length(), false); //for ivectors storing the no
No_of_BlockErrors.set_size(SNRdB.length(),false); //of errors bits or error frames
No_of_Blocks.set_size(SNRdB.length(),false);
No_of_Errors.clear();
No_of_Bits.clear();
No_of_BlockErrors.clear();
No_of_Blocks.clear();
printf ( "!SNR(dB)\tEbN0(dB)\tBER\t\tFER\t\tnrof Frames\n");
fprintf(f,"!SNR(dB)\tEbN0(dB)\tBER\t\tFER\t\tnrof Frames\n");
for(i=0; i< SNRdB.length(); i++)
{
//Set channel noise level
awgn_channel.set_noise(N0(i));
for(j=0;j<max_nrof_frame;j++)
{
//Generate random source bits
b_source_bits = randb(conv.get_info_bit_length());
//CONV encode
conv.encode_bits(b_source_bits, b_encoded_bits);
source_frame = psk.modulate_bits(b_encoded_bits);
// Fast Rayleigh channel + AWGN transmission
channel_gains = my_channel(channel_type, source_frame.length(), G_sd, ray_channel);
c_received_signals = elem_mult(source_frame, channel_gains);
c_received_signals = awgn_channel( c_received_signals );
//Demodulation to get llr
psk.demodulate_soft_bits(c_received_signals, channel_gains, N0(i), d_received_llr);
//Convert to Log(Pr=1/Pr=0)
d_received_llr = -1 * d_received_llr;
//CONV decode
conv.assign_apr_codeword(d_received_llr);
conv.decode(i_decoded_bits, i_decoded_symbols);
b_decoded_bits = to_bvec(i_decoded_bits.left(conv.get_info_bit_length()));
// remove dummy bits if trellis/code termination is used
berc.clear();
blerc.clear();
berc.count (b_source_bits, b_decoded_bits); //Count error bits in a word
blerc.count (b_source_bits, b_decoded_bits); //Count frame errors
No_of_Errors(i) += berc.get_errors(); //Updating counters
No_of_Bits(i) += berc.get_errors()+berc.get_corrects();
No_of_BlockErrors(i) +=blerc.get_errors();
No_of_Blocks(i)++;
if(No_of_Errors(i)>100000)
break;
}
ber(i) = (double)No_of_Errors(i)/No_of_Bits(i);
bler(i) = (double)No_of_BlockErrors(i)/No_of_Blocks(i);
double EbN0dB = SNRdB(i) - 10*log10(rate);
printf("%f\t%f\t%e\t%e\t%d\n", SNRdB(i), EbN0dB, ber(i), bler(i), No_of_Blocks(i));
fprintf(f,"%f\t%f\t%e\t%e\t%d\n", SNRdB(i), EbN0dB, ber(i), bler(i), No_of_Blocks(i));
if(ber(i)<1e-5) break;
}
fprintf(f,"!Elapsed time = %d s\n", tt.get_time()); //output simulation time
tt.toc(); //Stop timer and output simulation time
fclose(f); //close output file
return 0 ; //exit program
}
CORASMA_BER_Test::CORASMA_BER_Test()
{
modem=new Modem_CORASMA();
int L=1;
int OF=1;
cmat fading;
cvec channel1,channel2,channel3,channel4,channel5,channel6,channel7,channel8,channel9,channel10,channel11,channel12,channel13,channel14,channel15,channel16;
bvec transmitted_bits;
bvec received_bits;
cvec sum_chips;
cvec transmitted_symbols;
cvec received_chips;
double norm_fading;
BERC berc,berc1,berc2;
AWGN_Channel channel;
vec EbN0dB = linspace(1000, 1000, 1);
vec EbN0 = pow(10, EbN0dB / 10);
double Eb = 1.0;
vec N0 = Eb * pow(EbN0, -1.0);
int NumOfBits = modem->nb_bits;
int MaxIterations = 10;
int MaxNrOfErrors = 200;
int MinNrOfErrors = 5;
vec ber;
ber.set_size(EbN0dB.size(), false);
ber.clear();
RNG_randomize();
for (int i=0;i<EbN0dB.length();i++){
cout << endl << "Simulating point nr " << i + 1 << endl;
berc.clear();
berc1.clear();
berc2.clear();
channel.set_noise(N0(i));
for (int j=0;j<MaxIterations;j++) {
transmitted_bits = randb(NumOfBits);
sum_chips=modem->modulate(transmitted_bits);
transmitted_symbols.set_length(sum_chips.length()+L+1);
transmitted_symbols.zeros();
fading.set_size(L,sum_chips.length());
fading.zeros();
channel1.set_length(sum_chips.length());
/* channel2.set_length(sum_chips.length());
channel3.set_length(sum_chips.length());
channel4.set_length(sum_chips.length());
channel5.set_length(sum_chips.length());
channel6.set_length(sum_chips.length());
channel7.set_length(sum_chips.length());
channel8.set_length(sum_chips.length());
channel9.set_length(sum_chips.length());
channel10.set_length(sum_chips.length());
channel11.set_length(sum_chips.length());
channel12.set_length(sum_chips.length());
channel13.set_length(sum_chips.length());
channel14.set_length(sum_chips.length());
channel15.set_length(sum_chips.length());
channel16.set_length(sum_chips.length());*/
for(int k=0;k<sum_chips.length()/OF;k++){
channel1.replace_mid(k*OF,ones_c(OF));
/* channel1.replace_mid(k*OF,randn_c()*ones(OF));
channel2.replace_mid(k*OF,randn_c()*ones(OF));
channel3.replace_mid(k*OF,randn_c()*ones(OF));
channel4.replace_mid(k*OF,randn_c()*ones(OF));
channel5.replace_mid(k*OF,randn_c()*ones(OF));
channel6.replace_mid(k*OF,randn_c()*ones(OF));
channel7.replace_mid(k*OF,randn_c()*ones(OF));
channel8.replace_mid(k*OF,randn_c()*ones(OF));
channel9.replace_mid(k*OF,randn_c()*ones(OF));
channel10.replace_mid(k*OF,randn_c()*ones(OF));
channel11.replace_mid(k*OF,randn_c()*ones(OF));
channel12.replace_mid(k*OF,randn_c()*ones(OF));
channel13.replace_mid(k*OF,randn_c()*ones(OF));
channel14.replace_mid(k*OF,randn_c()*ones(OF));
channel15.replace_mid(k*OF,randn_c()*ones(OF));
channel16.replace_mid(k*OF,randn_c()*ones(OF));*/
}
norm_fading=1./sqrt(inv_dB(0)*norm(channel1)*norm(channel1)/sum_chips.length()/*+inv_dB(0)*norm(channel2)*norm(channel2)/sum_chips.length()+inv_dB(0)*norm(channel3)*norm(channel3)/sum_chips.length()+inv_dB(0)*norm(channel4)*norm(channel4)/sum_chips.length()+inv_dB(0)*norm(channel5)*norm(channel5)/sum_chips.length()+inv_dB(0)*norm(channel6)*norm(channel6)/sum_chips.length()+inv_dB(0)*norm(channel7)*norm(channel7)/sum_chips.length()+inv_dB(0)*norm(channel8)*norm(channel8)/sum_chips.length()+inv_dB(0)*norm(channel9)*norm(channel9)/sum_chips.length()+inv_dB(0)*norm(channel10)*norm(channel10)/sum_chips.length()+inv_dB(0)*norm(channel11)*norm(channel11)/sum_chips.length()+inv_dB(0)*norm(channel12)*norm(channel12)/sum_chips.length()+inv_dB(0)*norm(channel13)*norm(channel13)/sum_chips.length()+inv_dB(0)*norm(channel14)*norm(channel14)/sum_chips.length()+inv_dB(0)*norm(channel15)*norm(channel15)/sum_chips.length()+inv_dB(0)*norm(channel16)*norm(channel16)/sum_chips.length()*/);
fading.set_row(0,norm_fading*channel1);
/* fading.set_row(1,norm_fading*channel2);
fading.set_row(2,norm_fading*channel3);
fading.set_row(3,norm_fading*channel4);
fading.set_row(4,norm_fading*channel5);
fading.set_row(5,norm_fading*channel6);
fading.set_row(6,norm_fading*channel7);
fading.set_row(7,norm_fading*channel8);
fading.set_row(8,norm_fading*channel9);
fading.set_row(9,norm_fading*channel10);
fading.set_row(10,norm_fading*channel11);
fading.set_row(11,norm_fading*channel12);
fading.set_row(12,norm_fading*channel13);
fading.set_row(13,norm_fading*channel14);
fading.set_row(14,norm_fading*channel15);
fading.set_row(15,norm_fading*channel16);*/
for (int k=0;k<L;k++){
transmitted_symbols+=concat(zeros_c(k),elem_mult(to_cvec(sum_chips),fading.get_row(k)),zeros_c(L+1-k));
}
received_chips = channel(/*transmitted_symbols*/sum_chips);
cvec constellation;
int time_offset_estimate;
received_bits=modem->demodulate(received_chips,constellation,time_offset_estimate);
bvec received_bits_inverted=received_bits+bin(1);
//Generic Transmitter + First Receiver M&M + Costas
berc1.count(transmitted_bits, received_bits);
ber(i) = berc1.get_errorrate();
berc=berc1;
berc2.count(transmitted_bits, received_bits_inverted);
if(berc2.get_errorrate()<ber(i)){
ber(i) = berc2.get_errorrate();
berc=berc2;
}
cout << " Iteration " << j + 1 << ": ber = " << berc.get_errorrate() << endl;
if (berc.get_errors() > MaxNrOfErrors) {
cout << "Breaking on point " << i + 1 << " with " << berc.get_errors() << " errors." << endl;
break;
}
}
if (berc.get_errors() < MinNrOfErrors) {
cout << "Exiting Simulation on point " << i + 1 << endl;
break;
}
}
//Print results:
cout << endl;
cout << "EbN0dB = " << EbN0dB << endl;
cout << "ber = " << ber << endl;
}
MCDAAOFDM_BER_Test::MCDAAOFDM_BER_Test()
{
modem=new Modem_MCDAAOFDM();
int L=1;
int quasi_static=modem->Nfft+modem->Ncp;
cmat fading;
cvec channel1,channel2,channel3,channel4,channel5,channel6,channel7,channel8,channel9,channel10,channel11,channel12,channel13,channel14,channel15,channel16;
bvec transmitted_bits;
bvec received_bits;
cvec modulated_ofdm;
cvec transmitted_symbols;
cvec received_ofdm;
double norm_fading;
BERC berc;
AWGN_Channel channel;
vec EbN0dB = linspace(0, 40, 41);
vec EbN0 = pow(10, EbN0dB / 10);
double Eb = 1.0;
vec N0 = Eb * pow(EbN0, -1.0);
int NumOfBits = 1000000;
int MaxIterations = 10;
int MaxNrOfErrors = 200;
int MinNrOfErrors = 5;
vec ber;
ber.set_size(EbN0dB.size(), false);
ber.clear();
RNG_randomize();
for (int i=0;i<EbN0dB.length();i++){
cout << endl << "Simulating point nr " << i + 1 << endl;
berc.clear();
channel.set_noise(N0(i));
for (int j=0;j<MaxIterations;j++) {
transmitted_bits = randb(NumOfBits);
modulated_ofdm=sqrt(modem->Nfft+modem->Ncp)/sqrt(modem->Nfft)*modem->modulate_mask_qpsk(transmitted_bits,0);
transmitted_symbols.set_length(modulated_ofdm.length()+L+1);
transmitted_symbols.zeros();
fading.set_size(L,modulated_ofdm.length());
fading.zeros();
channel1.set_length(modulated_ofdm.length());
/* channel2.set_length(modulated_ofdm.length());
channel3.set_length(modulated_ofdm.length());
channel4.set_length(modulated_ofdm.length());
channel5.set_length(modulated_ofdm.length());
channel6.set_length(modulated_ofdm.length());
channel7.set_length(modulated_ofdm.length());
channel8.set_length(modulated_ofdm.length());
channel9.set_length(modulated_ofdm.length());
channel10.set_length(modulated_ofdm.length());
channel11.set_length(modulated_ofdm.length());
channel12.set_length(modulated_ofdm.length());
channel13.set_length(modulated_ofdm.length());
channel14.set_length(modulated_ofdm.length());
channel15.set_length(modulated_ofdm.length());
channel16.set_length(modulated_ofdm.length());*/
for(int k=0;k<modulated_ofdm.length()/quasi_static;k++){
channel1.replace_mid(k*quasi_static,ones_c(quasi_static));
//complex<double> random_complex= randn_c();
//double canal=sqrt(real(random_complex*conj(random_complex)));
//channel1.replace_mid(k*quasi_static,canal*ones_c(quasi_static));
//channel1.replace_mid(k*quasi_static,randn_c()*ones(quasi_static));
/* channel2.replace_mid(k*quasi_static,randn_c()*ones(quasi_static));
channel3.replace_mid(k*quasi_static,randn_c()*ones(quasi_static));
channel4.replace_mid(k*quasi_static,randn_c()*ones(quasi_static));
channel5.replace_mid(k*quasi_static,randn_c()*ones(quasi_static));
channel6.replace_mid(k*quasi_static,randn_c()*ones(quasi_static));
channel7.replace_mid(k*quasi_static,randn_c()*ones(quasi_static));
channel8.replace_mid(k*quasi_static,randn_c()*ones(quasi_static));
channel9.replace_mid(k*quasi_static,randn_c()*ones(quasi_static));
channel10.replace_mid(k*quasi_static,randn_c()*ones(quasi_static));
channel11.replace_mid(k*quasi_static,randn_c()*ones(quasi_static));
channel12.replace_mid(k*quasi_static,randn_c()*ones(quasi_static));
channel13.replace_mid(k*quasi_static,randn_c()*ones(quasi_static));
channel14.replace_mid(k*quasi_static,randn_c()*ones(quasi_static));
channel15.replace_mid(k*quasi_static,randn_c()*ones(quasi_static));
channel16.replace_mid(k*quasi_static,randn_c()*ones(quasi_static));*/
}
norm_fading=1./sqrt(inv_dB(0)*norm(channel1)*norm(channel1)/modulated_ofdm.length()/*+inv_dB(0)*norm(channel2)*norm(channel2)/modulated_ofdm.length()+inv_dB(0)*norm(channel3)*norm(channel3)/modulated_ofdm.length()+inv_dB(0)*norm(channel4)*norm(channel4)/modulated_ofdm.length()+inv_dB(0)*norm(channel5)*norm(channel5)/modulated_ofdm.length()+inv_dB(0)*norm(channel6)*norm(channel6)/modulated_ofdm.length()+inv_dB(0)*norm(channel7)*norm(channel7)/modulated_ofdm.length()+inv_dB(0)*norm(channel8)*norm(channel8)/modulated_ofdm.length()+inv_dB(0)*norm(channel9)*norm(channel9)/modulated_ofdm.length()+inv_dB(0)*norm(channel10)*norm(channel10)/modulated_ofdm.length()+inv_dB(0)*norm(channel11)*norm(channel11)/modulated_ofdm.length()+inv_dB(0)*norm(channel12)*norm(channel12)/modulated_ofdm.length()+inv_dB(0)*norm(channel13)*norm(channel13)/modulated_ofdm.length()+inv_dB(0)*norm(channel14)*norm(channel14)/modulated_ofdm.length()+inv_dB(0)*norm(channel15)*norm(channel15)/modulated_ofdm.length()+inv_dB(0)*norm(channel16)*norm(channel16)/modulated_ofdm.length()*/);
fading.set_row(0,norm_fading*channel1);
/* fading.set_row(1,norm_fading*channel2);
fading.set_row(2,norm_fading*channel3);
fading.set_row(3,norm_fading*channel4);
fading.set_row(4,norm_fading*channel5);
fading.set_row(5,norm_fading*channel6);
fading.set_row(6,norm_fading*channel7);
fading.set_row(7,norm_fading*channel8);
fading.set_row(8,norm_fading*channel9);
fading.set_row(9,norm_fading*channel10);
fading.set_row(10,norm_fading*channel11);
fading.set_row(11,norm_fading*channel12);
fading.set_row(12,norm_fading*channel13);
fading.set_row(13,norm_fading*channel14);
fading.set_row(14,norm_fading*channel15);
fading.set_row(15,norm_fading*channel16);*/
for (int k=0;k<L;k++){
transmitted_symbols+=concat(zeros_c(k),elem_mult(to_cvec(modulated_ofdm),fading.get_row(k)),zeros_c(L+1-k));
}
received_ofdm = channel(transmitted_symbols);
//received_chips = sum_chips;
cvec constellation;
vec estimated_channel;
double metric;
//bool is_ofdm=modem->detection(received_ofdm,metric);
modem->time_offset_estimate=0;
modem->frequency_offset_estimate=0;
cvec demodulated_ofdm_symbols=modem->equalizer_fourth_power(received_ofdm,0,estimated_channel);
received_bits=modem->demodulate_mask_gray_qpsk(demodulated_ofdm_symbols,0,constellation);
berc.count(transmitted_bits, received_bits);
ber(i) = berc.get_errorrate();
cout << " Iteration " << j + 1 << ": ber = " << berc.get_errorrate() << endl;
if (berc.get_errors() > MaxNrOfErrors) {
cout << "Breaking on point " << i + 1 << " with " << berc.get_errors() << " errors." << endl;
break;
}
}
if (berc.get_errors() < MinNrOfErrors) {
cout << "Exiting Simulation on point " << i + 1 << endl;
break;
}
}
//Print results:
cout << endl;
cout << "EbN0dB = " << EbN0dB << endl;
cout << "ber = " << ber << endl;
}
//Correlation
void xcorr(const cvec &x, const cvec &y, cvec &out, const int max_lag, const std::string scaleopt, bool autoflag)
{
int N = std::max(x.length(), y.length());
//Compute the FFT size as the "next power of 2" of the input vector's length (max)
int b = ceil_i(::log2(2.0 * N - 1));
int fftsize = pow2i(b);
int end = fftsize - 1;
cvec temp2;
if (autoflag == true) {
//Take FFT of input vector
cvec X = fft(zero_pad(x, fftsize));
//Compute the abs(X).^2 and take the inverse FFT.
temp2 = ifft(elem_mult(X, conj(X)));
}
else {
//Take FFT of input vectors
cvec X = fft(zero_pad(x, fftsize));
cvec Y = fft(zero_pad(y, fftsize));
//Compute the crosscorrelation
temp2 = ifft(elem_mult(X, conj(Y)));
}
// Compute the total number of lags to keep. We truncate the maximum number of lags to N-1.
int maxlag;
if ((max_lag == -1) || (max_lag >= N))
maxlag = N - 1;
else
maxlag = max_lag;
//Move negative lags to the beginning of the vector. Drop extra values from the FFT/IFFt
if (maxlag == 0) {
out.set_size(1, false);
out = temp2(0);
}
else
out = concat(temp2(end - maxlag + 1, end), temp2(0, maxlag));
//Scale data
if (scaleopt == "biased")
//out = out / static_cast<double_complex>(N);
out = out / static_cast<std::complex<double> >(N);
else if (scaleopt == "unbiased") {
//Total lag vector
vec lags = linspace(-maxlag, maxlag, 2 * maxlag + 1);
cvec scale = to_cvec(static_cast<double>(N) - abs(lags));
out /= scale;
}
else if (scaleopt == "coeff") {
if (autoflag == true) // Normalize by Rxx(0)
out /= out(maxlag);
else { //Normalize by sqrt(Rxx(0)*Ryy(0))
double rxx0 = sum(abs(elem_mult(x, x)));
double ryy0 = sum(abs(elem_mult(y, y)));
out /= std::sqrt(rxx0 * ryy0);
}
}
else if (scaleopt == "none") {}
else
it_warning("Unknow scaling option in XCORR, defaulting to <none> ");
}