source: git/Singular/fglmvec.cc @ 18dd47

// emacs edit mode for this file is -*- C++ -*-
// $Id: fglmvec.cc,v 1.3 1997-03-27 20:23:37 obachman Exp $

/****************************************
*  Computer Algebra System SINGULAR     *
****************************************/
/* 
* ABSTRACT - The FGLM-Algorithm
*   Implementation of number-vectors for the fglm algorithm.
*   (See fglm.cc). Based on a letter-envelope implementation, mainly
*   written to be used by the fglm algorithm. Hence they are 
*   specialized for this purpose.
*/

#include "mod2.h"

#ifdef HAVE_FGLM
#include "mmemory.h"
#include "structs.h"
#include "numbers.h"
#include "fglm.h"
#include "fglmvec.h"

class fglmVectorRep
{
private:
    int ref_count;
    int N;
    number * elems;
public:
    fglmVectorRep() : ref_count(1), N(0), elems(0) {}
    fglmVectorRep( int n, number * e ) : ref_count(1), N(n), elems(e) {}
    fglmVectorRep( int n ) : ref_count(1), N(n) 
    {
        fglmASSERT( N >= 0, "illegal Vector representation" );
        if ( N == 0 ) 
            elems= 0;
        else {
            elems= (number *)Alloc( N*sizeof( number ) );
            for ( int i= N-1; i >= 0; i-- )
                elems[i]= nInit( 0 );
        }
    }
    ~fglmVectorRep()
    {
        if ( N > 0 ) {
            for ( int i= N-1; i >= 0; i-- )
                nDelete( elems + i );
            Free( (ADDRESS)elems, N*sizeof( number ) );
        }
    }

    fglmVectorRep* clone() const
    {
        if ( N > 0 ) {
            number * elems_clone;
            elems_clone= (number *)Alloc( N*sizeof( number ) );
            for ( int i= N-1; i >= 0; i-- )
                elems_clone[i] = nCopy( elems[i] );
            return new fglmVectorRep( N, elems_clone );
        } else
            return new fglmVectorRep( N, 0 );
    }
    BOOLEAN deleteObject() { return --ref_count == 0; }
    fglmVectorRep * copyObject() { ref_count++; return this; }
    int refcount() const { return ref_count; }
    BOOLEAN isUnique() const { return ref_count == 1; }

    int size() const { return N; }
    int isZero() const 
    {
        int k;
        for ( k= N; k > 0; k-- )
            if ( ! nIsZero( getconstelem( k ) ) )
                return 0;
        return 1;
    }
    int numNonZeroElems() const 
    {
        int num = 0;
        int k;
        for ( k= N; k > 0; k-- )
            if ( ! nIsZero( getconstelem( k ) ) ) num++;
        return num;
    }
    void setelem( int i, number n )
    {
        fglmASSERT( 0 < i && i <= N, "setelem: wrong index" );
        nDelete( elems + i-1 );
        elems[i-1]= n;
    }
    number ejectelem( int i, number n ) 
    {
        fglmASSERT( isUnique(), "should only be called if unique!" );
        number temp= elems[i-1];
        elems[i-1]= n;
        return temp;
    }
    number & getelem( int i )
    {
        fglmASSERT( 0 < i && i <= N, "getelem: wrong index" );
        return elems[i-1];
    }
    const number getconstelem( int i) const
    {
        fglmASSERT( 0 < i && i <= N, "getconstelem: wrong index" );
        return elems[i-1];
    }
    friend class fglmVector;
};


///--------------------------------------------------------------------------------
/// Implementation of class fglmVector
///--------------------------------------------------------------------------------

fglmVector::fglmVector( fglmVectorRep * r ) : rep(r) {}

fglmVector::fglmVector() : rep( new fglmVectorRep() ) {}

fglmVector::fglmVector( int size ) : rep( new fglmVectorRep( size ) ) {}

fglmVector::fglmVector( int size, int basis ) : rep( new fglmVectorRep( size ) )
{
    rep->setelem( basis, nInit( 1 ) );
}

fglmVector::fglmVector( const fglmVector & v )
{
    rep= v.rep->copyObject();
}

fglmVector::~fglmVector()
{
    if ( rep->deleteObject() )
        delete rep;
}

void 
fglmVector::makeUnique()
{
    if ( rep->refcount() != 1 ) {
        rep->deleteObject();
        rep= rep->clone();
    }
}

int 
fglmVector::size() const
{
    return rep->size();
}

int
fglmVector::numNonZeroElems() const
{
    return rep->numNonZeroElems();
}

void
fglmVector::nihilate( const number fac1, const number fac2, const fglmVector v ) 
{
    int i;
    int vsize= v.size();
    number term1, term2;
    fglmASSERT( vsize <= rep->size(), "v has to be smaller oder equal" );
    if ( rep->isUnique() ) {
        for ( i= vsize; i > 0; i-- ) {
            term1= nMult( fac1, rep->getconstelem( i ) );
            term2= nMult( fac2, v.rep->getconstelem( i ) );
            rep->setelem( i, nSub( term1, term2 ) );
            nDelete( &term1 );
            nDelete( &term2 );
        }
        for ( i= rep->size(); i > vsize; i-- ) {
            rep->setelem( i, nMult( fac1, rep->getconstelem( i ) ) );
        }
    }
    else 
    {
        number* newelems;
        newelems= (number *)Alloc( rep->size()*sizeof( number ) );
        for ( i= vsize; i > 0; i-- ) {
            term1= nMult( fac1, rep->getconstelem( i ) );
            term2= nMult( fac2, v.rep->getconstelem( i ) );
            newelems[i-1]= nSub( term1, term2 );
            nDelete( &term1 );
            nDelete( &term2 );
        }
        for ( i= rep->size(); i > vsize; i-- ) {
            newelems[i-1]= nMult( fac1, rep->getconstelem( i ) );
        }
        rep->deleteObject();
        rep= new fglmVectorRep( rep->size(), newelems );
    }
}

fglmVector & 
fglmVector::operator = ( const fglmVector & v )
{
    if ( this != &v ) {
        if ( rep->deleteObject() )
            delete rep;
        rep = v.rep->copyObject();
    }
    return *this;
}

int
fglmVector::operator == ( const fglmVector & v )
{
    if ( rep->size() == v.rep->size() ) {
        if ( rep == v.rep ) return 1;
        else {
            int i;
            for ( i= rep->size(); i > 0; i-- )
                if ( ! nEqual( rep->getconstelem( i ), v.rep->getconstelem( i ) ) )
                    return 0;
            return 1;
        }
    }
    return 0;
}

int
fglmVector::operator != ( const fglmVector & v )
{
    return !( *this == v );
}

int 
fglmVector::isZero()
{
    return rep->isZero();
}

int 
fglmVector::elemIsZero( int i )
{
    return nIsZero( rep->getconstelem( i ) );
}

fglmVector &
fglmVector::operator += ( const fglmVector & v )
{
    fglmASSERT( size() == v.size(), "incompatible vectors" );
    // ACHTUNG : Das Verhalten hier mit gcd genau ueberpruefen!
    int i;
    if ( rep->isUnique() ) {
        for ( i= rep->size(); i > 0; i-- ) 
            rep->setelem( i, nAdd( rep->getconstelem( i ), v.rep->getconstelem( i ) ) );
    }
    else 
    {
        int n = rep->size();
        number* newelems;
        newelems= (number *)Alloc( n*sizeof( number ) );
        for ( i= n; i > 0; i-- )
            newelems[i-1]= nAdd( rep->getconstelem( i ), v.rep->getconstelem( i ) );
        rep->deleteObject();
        rep= new fglmVectorRep( n, newelems );
    }
    return *this;
}

fglmVector &
fglmVector::operator -= ( const fglmVector & v )
{
    fglmASSERT( size() == v.size(), "incompatible vectors" );
    int i;
    if ( rep->isUnique() ) {
        for ( i= rep->size(); i > 0; i-- ) 
            rep->setelem( i, nSub( rep->getconstelem( i ), v.rep->getconstelem( i ) ) );
    }
    else 
    {
        int n = rep->size();
        number* newelems;
        newelems= (number *)Alloc( n*sizeof( number ) );
        for ( i= n; i > 0; i-- )
            newelems[i-1]= nSub( rep->getconstelem( i ), v.rep->getconstelem( i ) );
        rep->deleteObject();
        rep= new fglmVectorRep( n, newelems );
    }
    return *this;
}

fglmVector &
fglmVector::operator *= ( const number & n )
{
    int s= rep->size();
    int i;
    if ( ! rep->isUnique() ) {
        number * temp;
        temp= (number *)Alloc( s*sizeof( number ) );
        for ( i= s; i > 0; i-- ) 
            temp[i-1]= nMult( rep->getconstelem( i ), n );
        rep->deleteObject();
        rep= new fglmVectorRep( s, temp );
    }
    else 
    {
        for (i= s; i > 0; i-- ) 
            rep->setelem( i, nMult( rep->getconstelem( i ), n ) );
    }
    return *this;
}

fglmVector &
fglmVector::operator /= ( const number & n )
{
    int s= rep->size();
    int i;
    if ( ! rep->isUnique() ) {
        number * temp;
        temp= (number *)Alloc( s*sizeof( number ) );
        for ( i= s; i > 0; i-- ) {
            temp[i-1]= nDiv( rep->getconstelem( i ), n );
            nNormalize( temp[i-1] );
        }
        rep->deleteObject();
        rep= new fglmVectorRep( s, temp );
    }
    else 
    {
        for (i= s; i > 0; i-- ) {
            rep->setelem( i, nDiv( rep->getconstelem( i ), n ) );
            nNormalize( rep->getelem( i ) );
        }
    }
    return *this;
}

fglmVector 
operator - ( const fglmVector & v ) 
{
    fglmVector temp( v.size() );
    int i;
    number n ;
    for ( i= v.size(); i > 0; i-- ) {
        n= nCopy( v.getconstelem( i ) );
        n= nNeg( n );
        temp.setelem( i, n );
    }
    return temp;
}

fglmVector 
operator + ( const fglmVector & lhs, const fglmVector & rhs ) 
{
    fglmVector temp= lhs;
    temp+= rhs;
    return temp;
}

fglmVector 
operator - ( const fglmVector & lhs, const fglmVector & rhs )
{
    fglmVector temp= lhs;
    temp-= rhs;
    return temp;
}

fglmVector 
operator * ( const fglmVector & v, const number n )
{
    fglmVector temp= v;
    temp*= n;
    return temp;
}

fglmVector
operator * ( const number n, const fglmVector & v )
{
    fglmVector temp= v;
    temp*= n;
    return temp;
}

number &
fglmVector::getelem( int i )
{
    makeUnique();
    return rep->getelem( i );
}

const number 
fglmVector::getconstelem( int i ) const
{
    return rep->getconstelem( i );
}

void
fglmVector::setelem( int i, number & n )
{
    makeUnique();
    rep->setelem( i, n );
    n= nNULL;
}

number 
fglmVector::gcd() const
{ 
    int i= rep->size();
    BOOLEAN found = FALSE;
    BOOLEAN gcdIsOne = FALSE;
    number theGcd;
    number current;
    while( i > 0 && ! found ) {
        current= rep->getconstelem( i );
        if ( ! nIsZero( current ) ) {
            theGcd= nCopy( current );
            found= TRUE;
            if ( ! nGreaterZero( theGcd ) ) {
                theGcd= nNeg( theGcd );
            }
            if ( nIsOne( theGcd ) ) gcdIsOne= TRUE;
        }
        i--;
    }
    if ( found ) {
        while ( i > 0 && ! gcdIsOne ) {
            current= rep->getconstelem( i );
            if ( ! nIsZero( current ) ) {
                number temp= nGcd( theGcd, current );
                nDelete( &theGcd );
                theGcd= temp;
                if ( nIsOne( theGcd ) ) gcdIsOne= TRUE;
            }
            i--;
        }
    }
    else 
        theGcd= nInit( 0 );
    return theGcd;
}

number
fglmVector::clearDenom() 
{
    number theLcm = nInit( 1 );
    number current;
    BOOLEAN isZero = TRUE;
    int i;
    for ( i= size(); i > 0; i-- ) {
        if ( ! nIsZero( rep->getconstelem(i) ) ) {
            isZero= FALSE;
            number temp= nLcm( theLcm, rep->getconstelem( i ) );
            nDelete( &theLcm );
            theLcm= temp;
        }
    }
    if ( isZero ) {
        nDelete( &theLcm );
        theLcm= nInit( 0 );
    }
    else {
        if ( ! nIsOne( theLcm ) ) {
            *this *= theLcm;
            for ( i= size(); i > 0; i-- ) {
                nNormalize( rep->getelem( i ) );
            }
        }
    }
    return theLcm;
}

#endif
// ----------------------------------------------------------------------------
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