quadrilateralcowboy/idlib/math/Polynomial.h

630 lines
16 KiB
C++

/*
===========================================================================
Doom 3 GPL Source Code
Copyright (C) 1999-2011 id Software LLC, a ZeniMax Media company.
This file is part of the Doom 3 GPL Source Code (?Doom 3 Source Code?).
Doom 3 Source Code is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Doom 3 Source Code is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Doom 3 Source Code. If not, see <http://www.gnu.org/licenses/>.
In addition, the Doom 3 Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU General Public License which accompanied the Doom 3 Source Code. If not, please request a copy in writing from id Software at the address below.
If you have questions concerning this license or the applicable additional terms, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.
===========================================================================
*/
#ifndef __MATH_POLYNOMIAL_H__
#define __MATH_POLYNOMIAL_H__
/*
===============================================================================
Polynomial of arbitrary degree with real coefficients.
===============================================================================
*/
class idPolynomial {
public:
idPolynomial( void );
explicit idPolynomial( int d );
explicit idPolynomial( float a, float b );
explicit idPolynomial( float a, float b, float c );
explicit idPolynomial( float a, float b, float c, float d );
explicit idPolynomial( float a, float b, float c, float d, float e );
float operator[]( int index ) const;
float & operator[]( int index );
idPolynomial operator-() const;
idPolynomial & operator=( const idPolynomial &p );
idPolynomial operator+( const idPolynomial &p ) const;
idPolynomial operator-( const idPolynomial &p ) const;
idPolynomial operator*( const float s ) const;
idPolynomial operator/( const float s ) const;
idPolynomial & operator+=( const idPolynomial &p );
idPolynomial & operator-=( const idPolynomial &p );
idPolynomial & operator*=( const float s );
idPolynomial & operator/=( const float s );
bool Compare( const idPolynomial &p ) const; // exact compare, no epsilon
bool Compare( const idPolynomial &p, const float epsilon ) const;// compare with epsilon
bool operator==( const idPolynomial &p ) const; // exact compare, no epsilon
bool operator!=( const idPolynomial &p ) const; // exact compare, no epsilon
void Zero( void );
void Zero( int d );
int GetDimension( void ) const; // get the degree of the polynomial
int GetDegree( void ) const; // get the degree of the polynomial
float GetValue( const float x ) const; // evaluate the polynomial with the given real value
idComplex GetValue( const idComplex &x ) const; // evaluate the polynomial with the given complex value
idPolynomial GetDerivative( void ) const; // get the first derivative of the polynomial
idPolynomial GetAntiDerivative( void ) const; // get the anti derivative of the polynomial
int GetRoots( idComplex *roots ) const; // get all roots
int GetRoots( float *roots ) const; // get the real roots
static int GetRoots1( float a, float b, float *roots );
static int GetRoots2( float a, float b, float c, float *roots );
static int GetRoots3( float a, float b, float c, float d, float *roots );
static int GetRoots4( float a, float b, float c, float d, float e, float *roots );
const float * ToFloatPtr( void ) const;
float * ToFloatPtr( void );
const char * ToString( int precision = 2 ) const;
static void Test( void );
private:
int degree;
int allocated;
float * coefficient;
void Resize( int d, bool keep );
int Laguer( const idComplex *coef, const int degree, idComplex &r ) const;
};
ID_INLINE idPolynomial::idPolynomial( void ) {
degree = -1;
allocated = 0;
coefficient = NULL;
}
ID_INLINE idPolynomial::idPolynomial( int d ) {
degree = -1;
allocated = 0;
coefficient = NULL;
Resize( d, false );
}
ID_INLINE idPolynomial::idPolynomial( float a, float b ) {
degree = -1;
allocated = 0;
coefficient = NULL;
Resize( 1, false );
coefficient[0] = b;
coefficient[1] = a;
}
ID_INLINE idPolynomial::idPolynomial( float a, float b, float c ) {
degree = -1;
allocated = 0;
coefficient = NULL;
Resize( 2, false );
coefficient[0] = c;
coefficient[1] = b;
coefficient[2] = a;
}
ID_INLINE idPolynomial::idPolynomial( float a, float b, float c, float d ) {
degree = -1;
allocated = 0;
coefficient = NULL;
Resize( 3, false );
coefficient[0] = d;
coefficient[1] = c;
coefficient[2] = b;
coefficient[3] = a;
}
ID_INLINE idPolynomial::idPolynomial( float a, float b, float c, float d, float e ) {
degree = -1;
allocated = 0;
coefficient = NULL;
Resize( 4, false );
coefficient[0] = e;
coefficient[1] = d;
coefficient[2] = c;
coefficient[3] = b;
coefficient[4] = a;
}
ID_INLINE float idPolynomial::operator[]( int index ) const {
assert( index >= 0 && index <= degree );
return coefficient[ index ];
}
ID_INLINE float& idPolynomial::operator[]( int index ) {
assert( index >= 0 && index <= degree );
return coefficient[ index ];
}
ID_INLINE idPolynomial idPolynomial::operator-() const {
int i;
idPolynomial n;
n = *this;
for ( i = 0; i <= degree; i++ ) {
n[i] = -n[i];
}
return n;
}
ID_INLINE idPolynomial &idPolynomial::operator=( const idPolynomial &p ) {
Resize( p.degree, false );
for ( int i = 0; i <= degree; i++ ) {
coefficient[i] = p.coefficient[i];
}
return *this;
}
ID_INLINE idPolynomial idPolynomial::operator+( const idPolynomial &p ) const {
int i;
idPolynomial n;
if ( degree > p.degree ) {
n.Resize( degree, false );
for ( i = 0; i <= p.degree; i++ ) {
n.coefficient[i] = coefficient[i] + p.coefficient[i];
}
for ( ; i <= degree; i++ ) {
n.coefficient[i] = coefficient[i];
}
n.degree = degree;
} else if ( p.degree > degree ) {
n.Resize( p.degree, false );
for ( i = 0; i <= degree; i++ ) {
n.coefficient[i] = coefficient[i] + p.coefficient[i];
}
for ( ; i <= p.degree; i++ ) {
n.coefficient[i] = p.coefficient[i];
}
n.degree = p.degree;
} else {
n.Resize( degree, false );
n.degree = 0;
for ( i = 0; i <= degree; i++ ) {
n.coefficient[i] = coefficient[i] + p.coefficient[i];
if ( n.coefficient[i] != 0.0f ) {
n.degree = i;
}
}
}
return n;
}
ID_INLINE idPolynomial idPolynomial::operator-( const idPolynomial &p ) const {
int i;
idPolynomial n;
if ( degree > p.degree ) {
n.Resize( degree, false );
for ( i = 0; i <= p.degree; i++ ) {
n.coefficient[i] = coefficient[i] - p.coefficient[i];
}
for ( ; i <= degree; i++ ) {
n.coefficient[i] = coefficient[i];
}
n.degree = degree;
} else if ( p.degree >= degree ) {
n.Resize( p.degree, false );
for ( i = 0; i <= degree; i++ ) {
n.coefficient[i] = coefficient[i] - p.coefficient[i];
}
for ( ; i <= p.degree; i++ ) {
n.coefficient[i] = - p.coefficient[i];
}
n.degree = p.degree;
} else {
n.Resize( degree, false );
n.degree = 0;
for ( i = 0; i <= degree; i++ ) {
n.coefficient[i] = coefficient[i] - p.coefficient[i];
if ( n.coefficient[i] != 0.0f ) {
n.degree = i;
}
}
}
return n;
}
ID_INLINE idPolynomial idPolynomial::operator*( const float s ) const {
idPolynomial n;
if ( s == 0.0f ) {
n.degree = 0;
} else {
n.Resize( degree, false );
for ( int i = 0; i <= degree; i++ ) {
n.coefficient[i] = coefficient[i] * s;
}
}
return n;
}
ID_INLINE idPolynomial idPolynomial::operator/( const float s ) const {
float invs;
idPolynomial n;
assert( s != 0.0f );
n.Resize( degree, false );
invs = 1.0f / s;
for ( int i = 0; i <= degree; i++ ) {
n.coefficient[i] = coefficient[i] * invs;
}
return n;
}
ID_INLINE idPolynomial &idPolynomial::operator+=( const idPolynomial &p ) {
int i;
if ( degree > p.degree ) {
for ( i = 0; i <= p.degree; i++ ) {
coefficient[i] += p.coefficient[i];
}
} else if ( p.degree > degree ) {
Resize( p.degree, true );
for ( i = 0; i <= degree; i++ ) {
coefficient[i] += p.coefficient[i];
}
for ( ; i <= p.degree; i++ ) {
coefficient[i] = p.coefficient[i];
}
} else {
for ( i = 0; i <= degree; i++ ) {
coefficient[i] += p.coefficient[i];
if ( coefficient[i] != 0.0f ) {
degree = i;
}
}
}
return *this;
}
ID_INLINE idPolynomial &idPolynomial::operator-=( const idPolynomial &p ) {
int i;
if ( degree > p.degree ) {
for ( i = 0; i <= p.degree; i++ ) {
coefficient[i] -= p.coefficient[i];
}
} else if ( p.degree > degree ) {
Resize( p.degree, true );
for ( i = 0; i <= degree; i++ ) {
coefficient[i] -= p.coefficient[i];
}
for ( ; i <= p.degree; i++ ) {
coefficient[i] = - p.coefficient[i];
}
} else {
for ( i = 0; i <= degree; i++ ) {
coefficient[i] -= p.coefficient[i];
if ( coefficient[i] != 0.0f ) {
degree = i;
}
}
}
return *this;
}
ID_INLINE idPolynomial &idPolynomial::operator*=( const float s ) {
if ( s == 0.0f ) {
degree = 0;
} else {
for ( int i = 0; i <= degree; i++ ) {
coefficient[i] *= s;
}
}
return *this;
}
ID_INLINE idPolynomial &idPolynomial::operator/=( const float s ) {
float invs;
assert( s != 0.0f );
invs = 1.0f / s;
for ( int i = 0; i <= degree; i++ ) {
coefficient[i] = invs;
}
return *this;;
}
ID_INLINE bool idPolynomial::Compare( const idPolynomial &p ) const {
if ( degree != p.degree ) {
return false;
}
for ( int i = 0; i <= degree; i++ ) {
if ( coefficient[i] != p.coefficient[i] ) {
return false;
}
}
return true;
}
ID_INLINE bool idPolynomial::Compare( const idPolynomial &p, const float epsilon ) const {
if ( degree != p.degree ) {
return false;
}
for ( int i = 0; i <= degree; i++ ) {
if ( idMath::Fabs( coefficient[i] - p.coefficient[i] ) > epsilon ) {
return false;
}
}
return true;
}
ID_INLINE bool idPolynomial::operator==( const idPolynomial &p ) const {
return Compare( p );
}
ID_INLINE bool idPolynomial::operator!=( const idPolynomial &p ) const {
return !Compare( p );
}
ID_INLINE void idPolynomial::Zero( void ) {
degree = 0;
}
ID_INLINE void idPolynomial::Zero( int d ) {
Resize( d, false );
for ( int i = 0; i <= degree; i++ ) {
coefficient[i] = 0.0f;
}
}
ID_INLINE int idPolynomial::GetDimension( void ) const {
return degree;
}
ID_INLINE int idPolynomial::GetDegree( void ) const {
return degree;
}
ID_INLINE float idPolynomial::GetValue( const float x ) const {
float y, z;
y = coefficient[0];
z = x;
for ( int i = 1; i <= degree; i++ ) {
y += coefficient[i] * z;
z *= x;
}
return y;
}
ID_INLINE idComplex idPolynomial::GetValue( const idComplex &x ) const {
idComplex y, z;
y.Set( coefficient[0], 0.0f );
z = x;
for ( int i = 1; i <= degree; i++ ) {
y += coefficient[i] * z;
z *= x;
}
return y;
}
ID_INLINE idPolynomial idPolynomial::GetDerivative( void ) const {
idPolynomial n;
if ( degree == 0 ) {
return n;
}
n.Resize( degree - 1, false );
for ( int i = 1; i <= degree; i++ ) {
n.coefficient[i-1] = i * coefficient[i];
}
return n;
}
ID_INLINE idPolynomial idPolynomial::GetAntiDerivative( void ) const {
idPolynomial n;
if ( degree == 0 ) {
return n;
}
n.Resize( degree + 1, false );
n.coefficient[0] = 0.0f;
for ( int i = 0; i <= degree; i++ ) {
n.coefficient[i+1] = coefficient[i] / ( i + 1 );
}
return n;
}
ID_INLINE int idPolynomial::GetRoots1( float a, float b, float *roots ) {
assert( a != 0.0f );
roots[0] = - b / a;
return 1;
}
ID_INLINE int idPolynomial::GetRoots2( float a, float b, float c, float *roots ) {
float inva, ds;
if ( a != 1.0f ) {
assert( a != 0.0f );
inva = 1.0f / a;
c *= inva;
b *= inva;
}
ds = b * b - 4.0f * c;
if ( ds < 0.0f ) {
return 0;
} else if ( ds > 0.0f ) {
ds = idMath::Sqrt( ds );
roots[0] = 0.5f * ( -b - ds );
roots[1] = 0.5f * ( -b + ds );
return 2;
} else {
roots[0] = 0.5f * -b;
return 1;
}
}
ID_INLINE int idPolynomial::GetRoots3( float a, float b, float c, float d, float *roots ) {
float inva, f, g, halfg, ofs, ds, dist, angle, cs, ss, t;
if ( a != 1.0f ) {
assert( a != 0.0f );
inva = 1.0f / a;
d *= inva;
c *= inva;
b *= inva;
}
f = ( 1.0f / 3.0f ) * ( 3.0f * c - b * b );
g = ( 1.0f / 27.0f ) * ( 2.0f * b * b * b - 9.0f * c * b + 27.0f * d );
halfg = 0.5f * g;
ofs = ( 1.0f / 3.0f ) * b;
ds = 0.25f * g * g + ( 1.0f / 27.0f ) * f * f * f;
if ( ds < 0.0f ) {
dist = idMath::Sqrt( ( -1.0f / 3.0f ) * f );
angle = ( 1.0f / 3.0f ) * idMath::ATan( idMath::Sqrt( -ds ), -halfg );
cs = idMath::Cos( angle );
ss = idMath::Sin( angle );
roots[0] = 2.0f * dist * cs - ofs;
roots[1] = -dist * ( cs + idMath::SQRT_THREE * ss ) - ofs;
roots[2] = -dist * ( cs - idMath::SQRT_THREE * ss ) - ofs;
return 3;
} else if ( ds > 0.0f ) {
ds = idMath::Sqrt( ds );
t = -halfg + ds;
if ( t >= 0.0f ) {
roots[0] = idMath::Pow( t, ( 1.0f / 3.0f ) );
} else {
roots[0] = -idMath::Pow( -t, ( 1.0f / 3.0f ) );
}
t = -halfg - ds;
if ( t >= 0.0f ) {
roots[0] += idMath::Pow( t, ( 1.0f / 3.0f ) );
} else {
roots[0] -= idMath::Pow( -t, ( 1.0f / 3.0f ) );
}
roots[0] -= ofs;
return 1;
} else {
if ( halfg >= 0.0f ) {
t = -idMath::Pow( halfg, ( 1.0f / 3.0f ) );
} else {
t = idMath::Pow( -halfg, ( 1.0f / 3.0f ) );
}
roots[0] = 2.0f * t - ofs;
roots[1] = -t - ofs;
roots[2] = roots[1];
return 3;
}
}
ID_INLINE int idPolynomial::GetRoots4( float a, float b, float c, float d, float e, float *roots ) {
int count;
float inva, y, ds, r, s1, s2, t1, t2, tp, tm;
float roots3[3];
if ( a != 1.0f ) {
assert( a != 0.0f );
inva = 1.0f / a;
e *= inva;
d *= inva;
c *= inva;
b *= inva;
}
count = 0;
GetRoots3( 1.0f, -c, b * d - 4.0f * e, -b * b * e + 4.0f * c * e - d * d, roots3 );
y = roots3[0];
ds = 0.25f * b * b - c + y;
if ( ds < 0.0f ) {
return 0;
} else if ( ds > 0.0f ) {
r = idMath::Sqrt( ds );
t1 = 0.75f * b * b - r * r - 2.0f * c;
t2 = ( 4.0f * b * c - 8.0f * d - b * b * b ) / ( 4.0f * r );
tp = t1 + t2;
tm = t1 - t2;
if ( tp >= 0.0f ) {
s1 = idMath::Sqrt( tp );
roots[count++] = -0.25f * b + 0.5f * ( r + s1 );
roots[count++] = -0.25f * b + 0.5f * ( r - s1 );
}
if ( tm >= 0.0f ) {
s2 = idMath::Sqrt( tm );
roots[count++] = -0.25f * b + 0.5f * ( s2 - r );
roots[count++] = -0.25f * b - 0.5f * ( s2 + r );
}
return count;
} else {
t2 = y * y - 4.0f * e;
if ( t2 >= 0.0f ) {
t2 = 2.0f * idMath::Sqrt( t2 );
t1 = 0.75f * b * b - 2.0f * c;
if ( t1 + t2 >= 0.0f ) {
s1 = idMath::Sqrt( t1 + t2 );
roots[count++] = -0.25f * b + 0.5f * s1;
roots[count++] = -0.25f * b - 0.5f * s1;
}
if ( t1 - t2 >= 0.0f ) {
s2 = idMath::Sqrt( t1 - t2 );
roots[count++] = -0.25f * b + 0.5f * s2;
roots[count++] = -0.25f * b - 0.5f * s2;
}
}
return count;
}
}
ID_INLINE const float *idPolynomial::ToFloatPtr( void ) const {
return coefficient;
}
ID_INLINE float *idPolynomial::ToFloatPtr( void ) {
return coefficient;
}
ID_INLINE void idPolynomial::Resize( int d, bool keep ) {
int alloc = ( d + 1 + 3 ) & ~3;
if ( alloc > allocated ) {
float *ptr = (float *) Mem_Alloc16( alloc * sizeof( float ) );
if ( coefficient != NULL ) {
if ( keep ) {
for ( int i = 0; i <= degree; i++ ) {
ptr[i] = coefficient[i];
}
}
Mem_Free16( coefficient );
}
allocated = alloc;
coefficient = ptr;
}
degree = d;
}
#endif /* !__MATH_POLYNOMIAL_H__ */