void fft_inv(double* x_int_re, double* x_int_im, int taille)
{
int size_2=taille>>1;
double base=2*M_PI/taille;
const double SQ_2=sqrt(2.0);//const double SQ_2=sqrt(2);
QVarLengthArray<double> pair_re(size_2), pair_im(size_2), impair_re(size_2), impair_im(size_2);//double pair_re[size_2], pair_im[size_2], impair_re[size_2], impair_im[size_2];
for(int i=0; i<size_2; i++){
int tmp1=i<<1;
pair_re[i]=x_int_re[tmp1];
pair_im[i]=x_int_im[tmp1];
impair_re[i]=x_int_re[tmp1+1];
impair_im[i]=x_int_im[tmp1+1];
}
if(taille>2){
fft_inv(pair_re.data(), pair_im.data(),size_2);//fft_inv(pair_re, pair_im,size_2);
fft_inv(impair_re.data(), impair_im.data(),size_2);//fft_inv(impair_re, impair_im,size_2);
}
for(int i=0; i<size_2; i++){
double tmp=base*i;
double tmpcos=cos(tmp);
double tmpsin=sin(tmp);
x_int_re[i]=(pair_re[i]+impair_re[i]*tmpcos-impair_im[i]*tmpsin)/SQ_2;
x_int_im[i]=(pair_im[i]+impair_im[i]*tmpcos+impair_re[i]*tmpsin)/SQ_2;
x_int_re[i+size_2]=(pair_re[i]-impair_re[i]*tmpcos+impair_im[i]*tmpsin)/SQ_2;
x_int_im[i+size_2]=(pair_im[i]-impair_im[i]*tmpcos-impair_re[i]*tmpsin)/SQ_2;
}
}
void fft2d_inv(double **xtre, double **xtim, double **xrec_re, double **xrec_im, int width, int height)
{
double **xint_re = Matrix::allocateMatrixData(height, width);
if (!xint_re)
return;
double **xint_im = Matrix::allocateMatrixData(height, width);
if (!xint_im){
Matrix::freeMatrixData(xint_re, height);
return;
}
#ifdef Q_CC_MSVC
QVarLengthArray<double> x_int_l(width), x_int2_l(width), x_int_c(height), x_int2_c(height);
#else
double x_int_l[width], x_int2_l[width], x_int_c[height], x_int2_c[height];
#endif
for(int k=0; k<height; k++){
for(int j=0; j<width; j++){
x_int_l[j] = xtre[(k-(height>>1))%height][(j+(width>>1))%width];
x_int2_l[j] = xtim[(k-(height>>1))%height][(j+(width>>1))%width] ;
}
#ifdef Q_CC_MSVC
fft_inv(x_int_l.data(), x_int2_l.data(), width) ;
#else
fft_inv(x_int_l, x_int2_l, width) ;
#endif
for(int j=0; j<width; j++){
xint_re[k][j] = x_int_l[j];
xint_im[k][j] = x_int2_l[j];
}
}
for(int k=0; k<width; k++){
for(int i=0; i<height; i++){
x_int_c[i] = xint_re[i][k];
x_int2_c[i] = xint_im[i][k];
}
#ifdef Q_CC_MSVC
fft_inv(x_int_c.data(),x_int2_c.data(), height) ;
#else
fft_inv(x_int_c,x_int2_c, height) ;
#endif
for(int i=0; i<height; i++){
xrec_re[i][k] = x_int_c[i];
xrec_im[i][k] = x_int2_c[i];
}
}
Matrix::freeMatrixData(xint_re, height);
Matrix::freeMatrixData(xint_im, height);
}
void fft2d_inv(double **xtre, double **xtim, double **xrec_re, double **xrec_im,
int width, int height) {
double **xint_re = Matrix::allocateMatrixData(height, width);
if (!xint_re)
return;
double **xint_im = Matrix::allocateMatrixData(height, width);
if (!xint_im) {
Matrix::freeMatrixData(xint_re, height);
return;
}
QVarLengthArray<double> x_int_l(width), x_int2_l(width), x_int_c(height),
x_int2_c(height); // double x_int_l[width], x_int2_l[width],
// x_int_c[height], x_int2_c[height];
for (int k = 0; k < height; k++) {
for (int j = 0; j < width; j++) {
int idx_h = (k + (height >> 1)) % height;
int idx_w = (j + (width >> 1)) % width;
x_int_l[j] = xtre[idx_h][idx_w];
x_int2_l[j] = xtim[idx_h][idx_w];
}
fft_inv(x_int_l.data(), x_int2_l.data(),
width); // fft_inv(x_int_l, x_int2_l, width) ;
for (int j = 0; j < width; j++) {
xint_re[k][j] = x_int_l[j];
xint_im[k][j] = x_int2_l[j];
}
}
for (int k = 0; k < width; k++) {
for (int i = 0; i < height; i++) {
x_int_c[i] = xint_re[i][k];
x_int2_c[i] = xint_im[i][k];
}
fft_inv(x_int_c.data(), x_int2_c.data(),
height); // fft_inv(x_int_c,x_int2_c, height) ;
for (int i = 0; i < height; i++) {
xrec_re[i][k] = x_int_c[i];
xrec_im[i][k] = x_int2_c[i];
}
}
Matrix::freeMatrixData(xint_re, height);
Matrix::freeMatrixData(xint_im, height);
}
void fft_inv(double* x_int_re, double* x_int_im, int taille)
{
int size_2 = taille >> 1, tmp1 = 0;
double tmp, tmpcos, tmpsin, base=2*M_PI/taille;
#ifdef Q_CC_MSVC
const double SQ_2=sqrt(2.0);
QVarLengthArray<double> pair_re(size_2), pair_im(size_2), impair_re(size_2), impair_im(size_2);
#else
const double SQ_2=sqrt(2);
double pair_re[size_2], pair_im[size_2], impair_re[size_2], impair_im[size_2];
#endif
for(int i=0; i<size_2; i++){
tmp1=i<<1;
pair_re[i]=x_int_re[tmp1];
pair_im[i]=x_int_im[tmp1];
impair_re[i]=x_int_re[tmp1+1];
impair_im[i]=x_int_im[tmp1+1];
}
if(taille>2){
#ifdef Q_CC_MSVC
fft_inv(pair_re.data(), pair_im.data(),size_2);
fft_inv(impair_re.data(), impair_im.data(),size_2);
#else
fft_inv(pair_re, pair_im,size_2);
fft_inv(impair_re, impair_im,size_2);
#endif
}
for(int i=0; i<size_2; i++){
tmp=base*i;
tmpcos=cos(tmp);
tmpsin=sin(tmp);
x_int_re[i]=(pair_re[i]+impair_re[i]*tmpcos-impair_im[i]*tmpsin)/SQ_2;
x_int_im[i]=(pair_im[i]+impair_im[i]*tmpcos+impair_re[i]*tmpsin)/SQ_2;
x_int_re[i+size_2]=(pair_re[i]-impair_re[i]*tmpcos+impair_im[i]*tmpsin)/SQ_2;
x_int_im[i+size_2]=(pair_im[i]-impair_im[i]*tmpcos-impair_re[i]*tmpsin)/SQ_2;
}
}
