JavaFFT变换代码

package ca.uol.aig.fftpack; /** * @author Baoshe Zhang * @author Astronomical Instrument Group of University of Lethbridge. */ class RealDoubleFFT_Mixed { /*------------------------------------------------- radf2: Real FFT's forward processing of factor 2 -------------------------------------------------*/ void radf2(int ido, int l1, final double cc[], double ch[], final double wtable[], int offset) { int i, k, ic; double ti2, tr2; int iw1; iw1 = offset; for(k=0; k<l1; k++) { ch[2*k*ido]=cc[k*ido]+cc[(k+l1)*ido]; ch[(2*k+1)*ido+ido-1]=cc[k*ido]-cc[(k+l1)*ido]; } if(ido<2) return; if(ido !=2) { for(k=0; k<l1; k++) { for(i=2; i<ido; i+=2) { ic=ido-i; tr2 = wtable[i-2+iw1]*cc[i-1+(k+l1)*ido] +wtable[i-1+iw1]*cc[i+(k+l1)*ido]; ti2 = wtable[i-2+iw1]*cc[i+(k+l1)*ido] -wtable[i-1+iw1]*cc[i-1+(k+l1)*ido]; ch[i+2*k*ido]=cc[i+k*ido]+ti2; ch[ic+(2*k+1)*ido]=ti2-cc[i+k*ido]; ch[i-1+2*k*ido]=cc[i-1+k*ido]+tr2; ch[ic-1+(2*k+1)*ido]=cc[i-1+k*ido]-tr2; } } if(ido%2==1)return; } for(k=0; k<l1; k++) { ch[(2*k+1)*ido]=-cc[ido-1+(k+l1)*ido]; ch[ido-1+2*k*ido]=cc[ido-1+k*ido]; } } /*------------------------------------------------- radb2: Real FFT's backward processing of factor 2 -------------------------------------------------*/ void radb2(int ido, int l1, final double cc[], double ch[], final double wtable[], int offset) { int i, k, ic; double ti2, tr2; int iw1 = offset; for(k=0; k<l1; k++) { ch[k*ido]=cc[2*k*ido]+cc[ido-1+(2*k+1)*ido]; ch[(k+l1)*ido]=cc[2*k*ido]-cc[ido-1+(2*k+1)*ido]; } if(ido<2) return; if(ido !=2) { for(k=0; k<l1;++k) { for(i=2; i<ido; i+=2) { ic=ido-i; ch[i-1+k*ido]=cc[i-1+2*k*ido]+cc[ic-1+(2*k+1)*ido]; tr2=cc[i-1+2*k*ido]-cc[ic-1+(2*k+1)*ido]; ch[i+k*ido]=cc[i+2*k*ido]-cc[ic+(2*k+1)*ido]; ti2=cc[i+(2*k)*ido]+cc[ic+(2*k+1)*ido]; ch[i-1+(k+l1)*ido]=wtable[i-2+iw1]*tr2-wtable[i-1+iw1]*ti2; ch[i+(k+l1)*ido]=wtable[i-2+iw1]*ti2+wtable[i-1+iw1]*tr2; } } if(ido%2==1) return; } for(k=0; k<l1; k++) { ch[ido-1+k*ido]=2*cc[ido-1+2*k*ido]; ch[ido-1+(k+l1)*ido]=-2*cc[(2*k+1)*ido]; } } /*------------------------------------------------- radf3: Real FFT's forward processing of factor 3 -------------------------------------------------*/ void radf3(int ido, int l1, final double cc[], double ch[], final double wtable[], int offset) { final double taur=-0.5D; final double taui=0.866025403784439D; int i, k, ic; double ci2, di2, di3, cr2, dr2, dr3, ti2, ti3, tr2, tr3; int iw1, iw2; iw1 = offset; iw2 = iw1 + ido; for(k=0; k<l1; k++) { cr2=cc[(k+l1)*ido]+cc[(k+2*l1)*ido]; ch[3*k*ido]=cc[k*ido]+cr2; ch[(3*k+2)*ido]=taui*(cc[(k+l1*2)*ido]-cc[(k+l1)*ido]); ch[ido-1+(3*k+1)*ido]=cc[k*ido]+taur*cr2; } if(ido==1) return; for(k=0; k<l1; k++) { for(i=2; i<ido; i+=2) { ic=ido-i; dr2 = wtable[i-2+iw1]*cc[i-1+(k+l1)*ido] +wtable[i-1+iw1]*cc[i+(k+l1)*ido]; di2 = wtable[i-2+iw1]*cc[i+(k+l1)*ido] -wtable[i-1+iw1]*cc[i-1+(k+l1)*ido]; dr3 = wtable[i-2+iw2]*cc[i-1+(k+l1*2)*ido] +wtable[i-1+iw2]*cc[i+(k+l1*2)*ido]; di3 = wtable[i-2+iw2]*cc[i+(k+l1*2)*ido] -wtable[i-1+iw2]*cc[i-1+(k+l1*2)*ido]; cr2 = dr2+dr3; ci2 = di2+di3; ch[i-1+3*k*ido]=cc[i-1+k*ido]+cr2; ch[i+3*k*ido]=cc[i+k*ido]+ci2; tr2=cc[i-1+k*ido]+taur*cr2; ti2=cc[i+k*ido]+taur*ci2; tr3=taui*(di2-di3); ti3=taui*(dr3-dr2); ch[i-1+(3*k+2)*ido]=tr2+tr3; ch[ic-1+(3*k+1)*ido]=tr2-tr3; ch[i+(3*k+2)*ido]=ti2+ti3; ch[ic+(3*k+1)*ido]=ti3-ti2; } } } /*------------------------------------------------- radb3: Real FFT's backward processing of factor 3 -------------------------------------------------*/ void radb3(int ido, int l1, final double cc[], double ch[], final double wtable[], int offset) { final double taur=-0.5D; final double taui=0.866025403784439D; int i, k, ic; double ci2, ci3, di2, di3, cr2, cr3, dr2, dr3, ti2, tr2; int iw1, iw2; iw1 = offset; iw2 = iw1 + ido; for(k=0; k<l1; k++) { tr2=2*cc[ido-1+(3*k+1)*ido]; cr2=cc[3*k*ido]+taur*tr2; ch[k*ido]=cc[3*k*ido]+tr2; ci3=2*taui*cc[(3*k+2)*ido]; ch[(k+l1)*ido]=cr2-ci3; ch[(k+2*l1)*ido]=cr2+ci3; } if(ido==1) return; for(k=0; k<l1; k++) { for(i=2; i<ido; i+=2) { ic=ido-i; tr2=cc[i-1+(3*k+2)*ido]+cc[ic-1+(3*k+1)*ido]; cr2=cc[i-1+3*k*ido]+taur*tr2; ch[i-1+k*ido]=cc[i-1+3*k*ido]+tr2; ti2=cc[i+(3*k+2)*ido]-cc[ic+(3*k+1)*ido]; ci2=cc[i+3*k*ido]+taur*ti2; ch[i+k*ido]=cc[i+3*k*ido]+ti2; cr3=taui*(cc[i-1+(3*k+2)*ido]-cc[ic-1+(3*k+1)*ido]); ci3=taui*(cc[i+(3*k+2)*ido]+cc[ic+(3*k+1)*ido]); dr2=cr2-ci3; dr3=cr2+ci3; di2=ci2+cr3; di3=ci2-cr3; ch[i-1+(k+l1)*ido] = wtable[i-2+iw1]*dr2 -wtable[i-1+iw1]*di2; ch[i+(k+l1)*ido] = wtable[i-2+iw1]*di2 +wtable[i-1+iw1]*dr2; ch[i-1+(k+2*l1)*ido] = wtable[i-2+iw2]*dr3 -wtable[i-1+iw2]*di3; ch[i+(k+2*l1)*ido] = wtable[i-2+iw2]*di3 +wtable[i-1+iw2]*dr3; } } } /*------------------------------------------------- radf4: Real FFT's forward processing of factor 4 -------------------------------------------------*/ void radf4(int ido, int l1, final double cc[], double ch[], final double wtable[], int offset) { final double hsqt2=0.7071067811865475D; int i, k, ic; double ci2, ci3, ci4, cr2, cr3, cr4, ti1, ti2, ti3, ti4, tr1, tr2, tr3, tr4; int iw1, iw2, iw3; iw1 = offset; iw2 = offset + ido; iw3 = iw2 + ido; for(k=0; k<l1; k++) { tr1=cc[(k+l1)*ido]+cc[(k+3*l1)*ido]; tr2=cc[k*ido]+cc[(k+2*l1)*ido]; ch[4*k*ido]=tr1+tr2; ch[ido-1+(4*k+3)*ido]=tr2-tr1; ch[ido-1+(4*k+1)*ido]=cc[k*ido]-cc[(k+2*l1)*ido]; ch[(4*k+2)*ido]=cc[(k+3*l1)*ido]-cc[(k+l1)*ido]; } if(ido<2) return; if(ido !=2) { for(k=0; k<l1; k++) { for(i=2; i<ido; i+=2) { ic=ido-i; cr2 = wtable[i-2+iw1]*cc[i-1+(k+l1)*ido] +wtable[i-1+iw1]*cc[i+(k+l1)*ido]; ci2 = wtable[i-2+iw1]*cc[i+(k+l1)*ido] -wtable[i-1+iw1]*cc[i-1+(k+l1)*ido]; cr3 = wtable[i-2+iw2]*cc[i-1+(k+2*l1)*ido] +wtable[i-1+iw2]*cc[i+(k+2*l1)*ido]; ci3 = wtable[i-2+iw2]*cc[i+(k+2*l1)*ido] -wtable[i-1+iw2]*cc[i-1+(k+2*l1)*ido]; cr4 = wtable[i-2+iw3]*cc[i-1+(k+3*l1)*ido]