svd.cpp
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00001 
00002 
00003 
00006 
00007 // Copyright (C) 1991,2,3,4,5: R B Davies
00008 // Updated 17 July, 1995
00009 
00010 #define WANT_MATH
00011 
00012 #include "include.h"
00013 #include "newmatap.h"
00014 #include "newmatrm.h"
00015 #include "precisio.h"
00016 
00017 #ifdef use_namespace
00018 namespace NEWMAT {
00019 #endif
00020 
00021 #ifdef DO_REPORT
00022 #define REPORT { static ExeCounter ExeCount(__LINE__,15); ++ExeCount; }
00023 #else
00024 #define REPORT {}
00025 #endif
00026 
00027 
00028 
00029 
00030 void SVD(const Matrix& A, DiagonalMatrix& Q, Matrix& U, Matrix& V,
00031    bool withU, bool withV)
00032 // from Wilkinson and Reinsch: "Handbook of Automatic Computation"
00033 {
00034    REPORT
00035    Tracer trace("SVD");
00036    Real eps = FloatingPointPrecision::Epsilon();
00037    Real tol = FloatingPointPrecision::Minimum()/eps;
00038 
00039    int m = A.Nrows(); int n = A.Ncols();
00040    if (m<n)
00041       Throw(ProgramException("Want no. Rows >= no. Cols", A));
00042    if (withV && &U == &V)
00043       Throw(ProgramException("Need different matrices for U and V", U, V));
00044    U = A; Real g = 0.0; Real f,h; Real x = 0.0; int i;
00045    RowVector E(n); RectMatrixRow EI(E,0); Q.ReSize(n);
00046    RectMatrixCol UCI(U,0); RectMatrixRow URI(U,0,1,n-1);
00047 
00048    if (n) for (i=0;;)
00049    {
00050       EI.First() = g; Real ei = g; EI.Right(); Real s = UCI.SumSquare();
00051       if (s<tol) { REPORT Q.element(i) = 0.0; }
00052       else
00053       {
00054          REPORT
00055          f = UCI.First(); g = -sign(sqrt(s), f); h = f*g-s; UCI.First() = f-g;
00056          Q.element(i) = g; RectMatrixCol UCJ = UCI; int j=n-i;
00057          while (--j) { UCJ.Right(); UCJ.AddScaled(UCI, (UCI*UCJ)/h); }
00058       }
00059 
00060       s = URI.SumSquare();
00061       if (s<tol) { REPORT g = 0.0; }
00062       else
00063       {
00064          REPORT
00065          f = URI.First(); g = -sign(sqrt(s), f); URI.First() = f-g;
00066          EI.Divide(URI,f*g-s); RectMatrixRow URJ = URI; int j=m-i;
00067          while (--j) { URJ.Down(); URJ.AddScaled(EI, URI*URJ); }
00068       }
00069 
00070       Real y = fabs(Q.element(i)) + fabs(ei); if (x<y) { REPORT x = y; }
00071       if (++i == n) { REPORT break; }
00072       UCI.DownDiag(); URI.DownDiag();
00073    }
00074 
00075    if (withV)
00076    {
00077       REPORT
00078       V.ReSize(n,n); V = 0.0; RectMatrixCol VCI(V,n-1,n-1,1);
00079       if (n) { VCI.First() = 1.0; g=E.element(n-1); if (n!=1) URI.UpDiag(); }
00080       for (i=n-2; i>=0; i--)
00081       {
00082          VCI.Left();
00083          if (g!=0.0)
00084          {
00085             VCI.Divide(URI, URI.First()*g); int j = n-i;
00086             RectMatrixCol VCJ = VCI;
00087             while (--j) { VCJ.Right(); VCJ.AddScaled( VCI, (URI*VCJ) ); }
00088          }
00089          VCI.Zero(); VCI.Up(); VCI.First() = 1.0; g=E.element(i);
00090          if (i==0) break;
00091          URI.UpDiag();
00092       }
00093    }
00094 
00095    if (withU)
00096    {
00097       REPORT
00098       for (i=n-1; i>=0; i--)
00099       {
00100          g = Q.element(i); URI.Reset(U,i,i+1,n-i-1); URI.Zero();
00101          if (g!=0.0)
00102          {
00103             h=UCI.First()*g; int j=n-i; RectMatrixCol UCJ = UCI;
00104             while (--j)
00105             {
00106                UCJ.Right(); UCI.Down(); UCJ.Down(); Real s = UCI*UCJ;
00107                UCI.Up(); UCJ.Up(); UCJ.AddScaled(UCI,s/h);
00108             }
00109             UCI.Divide(g);
00110          }
00111          else UCI.Zero();
00112          UCI.First() += 1.0;
00113          if (i==0) break;
00114          UCI.UpDiag();
00115       }
00116    }
00117 
00118    eps *= x;
00119    for (int k=n-1; k>=0; k--)
00120    {
00121       Real z = -FloatingPointPrecision::Maximum(); // to keep Gnu happy
00122       Real y; int limit = 50; int l = 0;
00123       while (limit--)
00124       {
00125          Real c, s; int i; int l1=k; bool tfc=false;
00126          for (l=k; l>=0; l--)
00127          {
00128 //          if (fabs(E.element(l))<=eps) goto test_f_convergence;
00129             if (fabs(E.element(l))<=eps) { REPORT tfc=true; break; }
00130             if (fabs(Q.element(l-1))<=eps) { REPORT l1=l; break; }
00131             REPORT
00132          }
00133          if (!tfc)
00134          {
00135             REPORT
00136             l=l1; l1=l-1; s = -1.0; c = 0.0;
00137             for (i=l; i<=k; i++)
00138             {
00139                f = - s * E.element(i); E.element(i) *= c;
00140 //             if (fabs(f)<=eps) goto test_f_convergence;
00141                if (fabs(f)<=eps) { REPORT break; }
00142                g = Q.element(i); h = pythag(g,f,c,s); Q.element(i) = h;
00143                if (withU)
00144                {
00145                   REPORT
00146                   RectMatrixCol UCI(U,i); RectMatrixCol UCJ(U,l1);
00147                   ComplexScale(UCJ, UCI, c, s);
00148                }
00149             }
00150          }
00151 //       test_f_convergence: z = Q.element(k); if (l==k) goto convergence;
00152          z = Q.element(k);  if (l==k) { REPORT break; }
00153 
00154          x = Q.element(l); y = Q.element(k-1);
00155          g = E.element(k-1); h = E.element(k);
00156          f = ((y-z)*(y+z) + (g-h)*(g+h)) / (2*h*y);
00157          if (f>1)         { REPORT g = f * sqrt(1 + square(1/f)); }
00158          else if (f<-1)   { REPORT g = -f * sqrt(1 + square(1/f)); }
00159          else             { REPORT g = sqrt(f*f + 1); }
00160             { REPORT f = ((x-z)*(x+z) + h*(y / ((f<0.0) ? f-g : f+g)-h)) / x; }
00161 
00162          c = 1.0; s = 1.0;
00163          for (i=l+1; i<=k; i++)
00164          {
00165             g = E.element(i); y = Q.element(i); h = s*g; g *= c;
00166             z = pythag(f,h,c,s); E.element(i-1) = z;
00167             f = x*c + g*s; g = -x*s + g*c; h = y*s; y *= c;
00168             if (withV)
00169             {
00170                REPORT
00171                RectMatrixCol VCI(V,i); RectMatrixCol VCJ(V,i-1);
00172                ComplexScale(VCI, VCJ, c, s);
00173             }
00174             z = pythag(f,h,c,s); Q.element(i-1) = z;
00175             f = c*g + s*y; x = -s*g + c*y;
00176             if (withU)
00177             {
00178                REPORT
00179                RectMatrixCol UCI(U,i); RectMatrixCol UCJ(U,i-1);
00180                ComplexScale(UCI, UCJ, c, s);
00181             }
00182          }
00183          E.element(l) = 0.0; E.element(k) = f; Q.element(k) = x;
00184       }
00185       if (l!=k) { Throw(ConvergenceException(A)); }
00186 // convergence:
00187       if (z < 0.0)
00188       {
00189          REPORT
00190          Q.element(k) = -z;
00191          if (withV) { RectMatrixCol VCI(V,k); VCI.Negate(); }
00192       }
00193    }
00194    if (withU & withV) SortSV(Q, U, V);
00195    else if (withU) SortSV(Q, U);
00196    else if (withV) SortSV(Q, V);
00197    else sort_descending(Q);
00198 }
00199 
00200 void SVD(const Matrix& A, DiagonalMatrix& D)
00201 { REPORT Matrix U; SVD(A, D, U, U, false, false); }
00202 
00203 
00204 
00205 #ifdef use_namespace
00206 }
00207 #endif
00208 


kni
Author(s): Martin Günther
autogenerated on Thu Jun 6 2019 21:42:34