#include <linalg.h>

Static Public Member Functions
static void	SymetricToTridiag (TFltVV &a, int n, TFltV &d, TFltV &e)

static void	EigSymmetricTridiag (TFltV &d, TFltV &e, int n, TFltVV &z)

static void	CholeskyDecomposition (TFltVV &A, TFltV &p)

static void	CholeskySolve (const TFltVV &A, const TFltV &p, const TFltV &b, TFltV &x)

static void	SolveSymetricSystem (TFltVV &A, const TFltV &b, TFltV &x)

static void	InverseSubstitute (TFltVV &A, const TFltV &p)

static void	InverseSymetric (TFltVV &A)

static void	InverseTriagonal (TFltVV &A)

static void	LUDecomposition (TFltVV &A, TIntV &indx, double &d)

static void	LUSolve (const TFltVV &A, const TIntV &indx, TFltV &b)

static void	SolveLinearSystem (TFltVV &A, const TFltV &b, TFltV &x)

Static Private Member Functions
static double	sqr (double a)

static double	sign (double a, double b)

static double	pythag (double a, double b)

static void	nrerror (const TStr &error_text)

Detailed Description

Definition at line 300 of file linalg.h.

Member Function Documentation

void TNumericalStuff::CholeskyDecomposition	(	TFltVV &	A,
		TFltV &	p
	)

static

Definition at line 797 of file linalg.cpp.

                                                                {
   Assert(A.GetRows() == A.GetCols());
   int n = A.GetRows(); p.Reserve(n,n);
 
   int i,j,k;
   double sum;
   for (i=1;i<=n;i++) {
     for (j=i;j<=n;j++) {
       for (sum=A(i-1,j-1),k=i-1;k>=1;k--) sum -= A(i-1,k-1)*A(j-1,k-1);
       if (i == j) {
         if (sum <= 0.0)
           nrerror("choldc failed");
         p[i-1]=sqrt(sum);
       } else A(j-1,i-1)=sum/p[i-1];
     }
   }
 }

void TNumericalStuff::CholeskySolve	(	const TFltVV &	A,
		const TFltV &	p,
		const TFltV &	b,
		TFltV &	x
	)

static

Definition at line 815 of file linalg.cpp.

                                                                                              {
   IAssert(A.GetRows() == A.GetCols());
   int n = A.GetRows(); x.Reserve(n,n);
 
   int i,k;
   double sum;
 
   // Solve L * y = b, storing y in x
   for (i=1;i<=n;i++) {
     for (sum=b[i-1],k=i-1;k>=1;k--)
       sum -= A(i-1,k-1)*x[k-1];
     x[i-1]=sum/p[i-1];
   }
 
   // Solve L^T * x = y
   for (i=n;i>=1;i--) {
     for (sum=x[i-1],k=i+1;k<=n;k++)
       sum -= A(k-1,i-1)*x[k-1];
     x[i-1]=sum/p[i-1];
   }
 }

void TNumericalStuff::EigSymmetricTridiag	(	TFltV &	d,
		TFltV &	e,
		int	n,
		TFltVV &	z
	)

static

Definition at line 740 of file linalg.cpp.

                                                                               {
     int m,l,iter,i,k; // N = n+1;
     double s,r,p,g,f,dd,c,b;
     // Convenient to renumber the elements of e
     for (i=2;i<=n;i++) e[i-1]=e[i];
     e[n]=0.0;
     for (l=1;l<=n;l++) {
         iter=0;
         do {
             // Look for a single small subdiagonal element to split the matrix.
             for (m=l;m<=n-1;m++) {
         dd=TFlt::Abs(d[m])+TFlt::Abs(d[m+1]);
                 if ((double)(TFlt::Abs(e[m])+dd) == dd) break;
             }
             if (m != l) {
                 if (iter++ == 60) nrerror("Too many iterations in EigSymmetricTridiag");
                 //Form shift.
                 g=(d[l+1]-d[l])/(2.0*e[l]);
                 r=pythag(g,1.0);
                 //This is dm - ks.
                 g=d[m]-d[l]+e[l]/(g+sign(r,g));
                 s=c=1.0;
                 p=0.0;
                 // A plane rotation as in the original QL, followed by
                 // Givens rotations to restore tridiagonal form
                 for (i=m-1;i>=l;i--) {
                     f=s*e[i];
                     b=c*e[i];
                     e[i+1]=(r=pythag(f,g));
                     // Recover from underflow.
                     if (r == 0.0) {
                         d[i+1] -= p;
                         e[m]=0.0;
                         break;
                     }
                     s=f/r;
                     c=g/r;
                     g=d[i+1]-p;
                     r=(d[i]-g)*s+2.0*c*b;
                     d[i+1]=g+(p=s*r);
                     g=c*r-b;
                     // Next loop can be omitted if eigenvectors not wanted
                     for (k=0;k<n;k++) {
                         f=z(k,i);
                         z(k,i)=s*z(k,i-1)+c*f;
                         z(k,i-1)=c*z(k,i-1)-s*f;
                     }
                 }
                 if (r == 0.0 && i >= l) continue;
                 d[l] -= p;
                 e[l]=g;
                 e[m]=0.0;
             }
         } while (m != l);
     }
 }

void TNumericalStuff::InverseSubstitute	(	TFltVV &	A,
		const TFltV &	p
	)

static

Definition at line 843 of file linalg.cpp.

                                                                  {
   IAssert(A.GetRows() == A.GetCols());
   int n = A.GetRows(); TFltV x(n);
 
     int i, j, k; double sum;
     for (i = 0; i < n; i++) {
       // solve L * y = e_i, store in x
         // elements from 0 to i-1 are 0.0
         for (j = 0; j < i; j++) x[j] = 0.0;
         // solve l_ii * y_i = 1 => y_i = 1/l_ii
         x[i] = 1/p[i];
         // solve y_j for j > i
         for (j = i+1; j < n; j++) {
             for (sum = 0.0, k = i; k < j; k++)
                 sum -= A(j,k) * x[k];
             x[j] = sum / p[j];
         }
 
       // solve L'* x = y, store in upper triangule of A
         for (j = n-1; j >= i; j--) {
             for (sum = x[j], k = j+1; k < n; k++)
                 sum -= A(k,j)*x[k];
             x[j] = sum/p[j];
         }
         for (int j = i; j < n; j++) A(i,j) = x[j];
     }
 
 }

void TNumericalStuff::InverseSymetric ( TFltVV & A )

static

Definition at line 872 of file linalg.cpp.

                                                {
     IAssert(A.GetRows() == A.GetCols());
     TFltV p;
     // first we calculate cholesky decomposition of A
     CholeskyDecomposition(A, p);
     // than we solve system A x_i = e_i for i = 1..n
     InverseSubstitute(A, p);
 }

void TNumericalStuff::InverseTriagonal ( TFltVV & A )

static

Definition at line 881 of file linalg.cpp.

                                                 {
   IAssert(A.GetRows() == A.GetCols());
   int n = A.GetRows(); TFltV x(n), p(n);
 
     int i, j, k; double sum;
     // copy upper triangle to lower one as we'll overwrite upper one
     for (i = 0; i < n; i++) {
         p[i] = A(i,i);
         for (j = i+1; j < n; j++)
             A(j,i) = A(i,j);
     }
     // solve
     for (i = 0; i < n; i++) {
         // solve R * x = e_i, store in x
         // elements from 0 to i-1 are 0.0
         for (j = n-1; j > i; j--) x[j] = 0.0;
         // solve l_ii * y_i = 1 => y_i = 1/l_ii
         x[i] = 1/p[i];
         // solve y_j for j > i
         for (j = i-1; j >= 0; j--) {
             for (sum = 0.0, k = i; k > j; k--)
                 sum -= A(k,j) * x[k];
             x[j] = sum / p[j];
         }
         for (int j = 0; j <= i; j++) A(j,i) = x[j];
     }
 }

void TNumericalStuff::LUDecomposition	(	TFltVV &	A,
		TIntV &	indx,
		double &	d
	)

static

Definition at line 909 of file linalg.cpp.

                                                                        {
   Assert(A.GetRows() == A.GetCols());
   int n = A.GetRows(); indx.Reserve(n,n);
 
     int i=0,imax=0,j=0,k=0;
     double big,dum,sum,temp;
     TFltV vv(n); // vv stores the implicit scaling of each row.
     d=1.0;       // No row interchanges yet.
 
     // Loop over rows to get the implicit scaling information.
     for (i=1;i<=n;i++) {
         big=0.0;
         for (j=1;j<=n;j++)
             if ((temp=TFlt::Abs(A(i-1,j-1))) > big) big=temp;
         if (big == 0.0) nrerror("Singular matrix in routine LUDecomposition");
         vv[i-1]=1.0/big;
     }
 
     for (j=1;j<=n;j++) {
         for (i=1;i<j;i++) {
             sum=A(i-1,j-1);
             for (k=1;k<i;k++) sum -= A(i-1,k-1)*A(k-1,j-1);
             A(i-1,j-1)=sum;
         }
         big=0.0; //Initialize for the search for largest pivot element.
         for (i=j;i<=n;i++) {
             sum=A(i-1,j-1);
             for (k=1;k<j;k++)
                 sum -= A(i-1,k-1)*A(k-1,j-1);
             A(i-1,j-1)=sum;
 
             //Is the figure of merit for the pivot better than the best so far?
             if ((dum=vv[i-1] * TFlt::Abs(sum)) >= big) {
                 big=dum;
                 imax=i;
             }
         }
 
         //Do we need to interchange rows?
         if (j != imax) {
             //Yes, do so...
             for (k=1;k<=n;k++) {
                 dum=A(imax-1,k-1);
             A(imax-1,k-1)=A(j-1,k-1); // Tadej: imax-1,k looks wrong
             A(j-1,k-1)=dum;
             }
             //...and change the parity of d.
             d = -d;
             vv[imax-1]=vv[j-1]; //Also interchange the scale factor.
         }
         indx[j-1]=imax;
 
         //If the pivot element is zero the matrix is singular (at least to the precision of the
         //algorithm). For some applications on singular matrices, it is desirable to substitute
         //TINY for zero.
         if (A(j-1,j-1) == 0.0) A(j-1,j-1)=1e-20;
 
          //Now, finally, divide by the pivot element.
         if (j != n) {
             dum=1.0/(A(j-1,j-1));
             for (i=j+1;i<=n;i++) A(i-1,j-1) *= dum;
         }
     } //Go back for the next column in the reduction.
 }

void TNumericalStuff::LUSolve	(	const TFltVV &	A,
		const TIntV &	indx,
		TFltV &	b
	)

static

Definition at line 974 of file linalg.cpp.

                                                                           {
   Assert(A.GetRows() == A.GetCols());
   int n = A.GetRows();
     int i,ii=0,ip,j;
     double sum;
     for (i=1;i<=n;i++) {
         ip=indx[i-1];
         sum=b[ip-1];
         b[ip-1]=b[i-1];
         if (ii)
             for (j=ii;j<=i-1;j++) sum -= A(i-1,j-1)*b[j-1];
         else if (sum) ii=i;b[i-1]=sum;
     }
     for (i=n;i>=1;i--) {
         sum=b[i-1];
         for (j=i+1;j<=n;j++) sum -= A(i-1,j-1)*b[j-1];
         b[i-1]=sum/A(i-1,i-1);
     }
 }

void TNumericalStuff::nrerror ( const TStr & error_text )

staticprivate

Definition at line 655 of file linalg.cpp.

                                                     {
     printf("NR_ERROR: %s", error_text.CStr());
     throw new TNSException(error_text);
 }

double TNumericalStuff::pythag	(	double	a,
		double	b
	)

staticprivate

Definition at line 660 of file linalg.cpp.

                                                  {
     double absa = fabs(a), absb = fabs(b);
     if (absa > absb)
         return absa*sqrt(1.0+sqr(absb/absa));
     else
         return (absb == 0.0 ? 0.0 : absb*sqrt(1.0+sqr(absa/absb)));
 }

double TNumericalStuff::sign	(	double	a,
		double	b
	)

staticprivate

Definition at line 651 of file linalg.cpp.

                                                {
   return b >= 0.0 ? fabs(a) : -fabs(a);
 }

void TNumericalStuff::SolveLinearSystem	(	TFltVV &	A,
		const TFltV &	b,
		TFltV &	x
	)

static

Definition at line 994 of file linalg.cpp.

                                                                            {
     TIntV indx; double d;
     LUDecomposition(A, indx, d);
     x = b;
     LUSolve(A, indx, x);
 }

void TNumericalStuff::SolveSymetricSystem	(	TFltVV &	A,
		const TFltV &	b,
		TFltV &	x
	)

static

Definition at line 837 of file linalg.cpp.

                                                                              {
   IAssert(A.GetRows() == A.GetCols());
   TFltV p; CholeskyDecomposition(A, p);
   CholeskySolve(A, p, b, x);
 }

double TNumericalStuff::sqr ( double a )

staticprivate

Definition at line 647 of file linalg.cpp.

                                     {
   return a == 0.0 ? 0.0 : a*a;
 }

void TNumericalStuff::SymetricToTridiag	(	TFltVV &	a,
		int	n,
		TFltV &	d,
		TFltV &	e
	)

static

Definition at line 668 of file linalg.cpp.

                                                                             {
     int l,k,j,i;
     double scale,hh,h,g,f;
     for (i=n;i>=2;i--) {
         l=i-1;
         h=scale=0.0;
         if (l > 1) {
             for (k=1;k<=l;k++)
                 scale += fabs(a(i-1,k-1).Val);
             if (scale == 0.0) //Skip transformation.
                 e[i]=a(i-1,l-1);
             else {
                 for (k=1;k<=l;k++) {
                     a(i-1,k-1) /= scale; //Use scaled a's for transformation.
                     h += a(i-1,k-1)*a(i-1,k-1);
                 }
                 f=a(i-1,l-1);
                 g=(f >= 0.0 ? -sqrt(h) : sqrt(h));
                 IAssertR(_isnan(g) == 0, TFlt::GetStr(h));
                 e[i]=scale*g;
                 h -= f*g; //Now h is equation (11.2.4).
                 a(i-1,l-1)=f-g; //Store u in the ith row of a.
                 f=0.0;
                 for (j=1;j<=l;j++) {
                     // Next statement can be omitted if eigenvectors not wanted
                     a(j-1,i-1)=a(i-1,j-1)/h; //Store u=H in ith column of a.
                     g=0.0; //Form an element of A  u in g.
                     for (k=1;k<=j;k++)
                         g += a(j-1,k-1)*a(i-1,k-1);
                     for (k=j+1;k<=l;k++)
                         g += a(k-1,j-1)*a(i-1,k-1);
                     e[j]=g/h; //Form element of p in temporarily unused element of e.
                     f += e[j]*a(i-1,j-1);
                 }
                 hh=f/(h+h); //Form K, equation (11.2.11).
                 for (j=1;j<=l;j++) { //Form q and store in e overwriting p.
                     f=a(i-1,j-1);
                     e[j]=g=e[j]-hh*f;
                     for (k=1;k<=j;k++) { //Reduce a, equation (11.2.13).
                         a(j-1,k-1) -= (f*e[k]+g*a(i-1,k-1));
                         Assert(_isnan(a(j-1,k-1)) == 0);
                     }
                 }
             }
         } else
             e[i]=a(i-1,l-1);
         d[i]=h;
     }
     // Next statement can be omitted if eigenvectors not wanted
     d[1]=0.0;
     e[1]=0.0;
     // Contents of this loop can be omitted if eigenvectors not
     // wanted except for statement d[i]=a[i][i];
     for (i=1;i<=n;i++) { //Begin accumulation of transformationmatrices.
         l=i-1;
         if (d[i]) { //This block skipped when i=1.
             for (j=1;j<=l;j++) {
                 g=0.0;
                 for (k=1;k<=l;k++) //Use u and u=H stored in a to form PQ.
                     g += a(i-1,k-1)*a(k-1,j-1);
                 for (k=1;k<=l;k++) {
                     a(k-1,j-1) -= g*a(k-1,i-1);
                     Assert(_isnan(a(k-1,j-1)) == 0);
                 }
             }
         }
         d[i]=a(i-1,i-1); //This statement remains.
         a(i-1,i-1)=1.0; //Reset row and column of a to identity  matrix for next iteration.
         for (j=1;j<=l;j++) a(j-1,i-1)=a(i-1,j-1)=0.0;
     }
 }

The documentation for this class was generated from the following files:

glib-core/linalg.h
glib-core/linalg.cpp

Static Public Member Functions

Static Private Member Functions

Detailed Description

Member Function Documentation