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EgtNumKernel :

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- corretta soluzione di equazione quadratica con coefficiente di x^2 molto piccolo.
This commit is contained in:
Dario Sassi
2019-05-22 14:49:19 +00:00
parent a975d94f3c
commit f19e7827fd
1 changed files with 9 additions and 5 deletions
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PolynomialRoots.cpp
+9 -5
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@@ -201,14 +201,14 @@ QuadraticPolynomialRoots( DBLVECTOR& vdPoly, DBLVECTOR& vdRoot, int* pnIter)
vdRoot.push_back( 0) ;
vdRoot.push_back( - vdPoly[1] / vdPoly[2]) ;
if ( vdRoot[0] < vdRoot[1])
swap( vdRoot[0], vdRoot[1]) ;
swap( vdRoot[0], vdRoot[1]) ;
return 2 ;
}
// caso generale
// caso generale ( x^2 + 2 p x + q = 0)
double p = vdPoly[1] / ( 2.0 * vdPoly[2]) ;
double q = vdPoly[0] / vdPoly[2] ;
double Delta = p * p - q ;
if ( abs( Delta) < DBL_EPSILON) {
if ( abs( Delta) < DBL_EPSILON * DBL_EPSILON) {
vdRoot.clear() ;
vdRoot.reserve( 1) ;
vdRoot.push_back( -p) ;
@@ -219,7 +219,11 @@ QuadraticPolynomialRoots( DBLVECTOR& vdPoly, DBLVECTOR& vdRoot, int* pnIter)
}
// Delta positivo
double dSqrtD = sqrt( Delta) ;
vdRoot.push_back( - p + dSqrtD) ;
vdRoot.push_back( - p - dSqrtD) ;
double r1 = -( p + copysign( dSqrtD, p)) ;
double r2 = q / r1 ;
if ( r1 > r2)
swap( r1, r2) ;
vdRoot.push_back( r1) ;
vdRoot.push_back( r2) ;
return 2 ;
}