/*
- poly.cc -- routines for manipulation of polynomials in one var
+ poly.cc -- routines for manipulation of polynomials in one var
(c) 1993--2005 Han-Wen Nienhuys <hanwen@cs.uu.nl>
- */
+*/
#include "polynomial.hh"
#include <cmath>
/*
- Een beter milieu begint bij uzelf. Hergebruik!
+ Een beter milieu begint bij uzelf. Hergebruik!
- This was ripped from Rayce, a raytracer I once wrote.
+ This was ripped from Rayce, a raytracer I once wrote.
*/
Real
Real p = 0.0;
// horner's scheme
- for (int i = coefs_.size (); i--; )
+ for (int i = coefs_.size (); i--;)
p = x * p + coefs_[i];
-
+
return p;
}
-
Polynomial
-Polynomial::multiply (const Polynomial & p1, const Polynomial & p2)
+Polynomial::multiply (const Polynomial &p1, const Polynomial &p2)
{
Polynomial dest;
if (i - j <= p2.degree () && j <= p1.degree ())
dest.coefs_.top () += p1.coefs_[j] * p2.coefs_[i - j];
}
-
+
return dest;
}
{
for (int i = 1; i<= degree (); i++)
{
- coefs_[i-1] = coefs_[i] * i;
+ coefs_[i - 1] = coefs_[i] * i;
}
coefs_.pop ();
}
Polynomial
-Polynomial::power (int exponent, const Polynomial & src)
+Polynomial::power (int exponent, const Polynomial &src)
{
int e = exponent;
Polynomial dest (1), base (src);
-
+
/*
classic int power. invariant: src^exponent = dest * src ^ e
greetings go out to Lex Bijlsma & Jaap vd Woude */
while (e > 0)
{
if (e % 2)
- {
+ {
dest = multiply (dest, base);
e--;
- } else
- {
- base = multiply (base, base);
- e /= 2;
- }
+ }
+ else
+
+ {
+ base = multiply (base, base);
+ e /= 2;
+ }
}
- return dest;
+ return dest;
}
static Real const FUDGE = 1e-8;
void
Polynomial::clean ()
{
-/*
- We only do relative comparisons. Absolute comparisons break down in
- degenerate cases. */
- while (degree () > 0 &&
- (fabs (coefs_.top ()) < FUDGE * fabs (coefs_.top (1))
- || !coefs_.top ()))
+ /*
+ We only do relative comparisons. Absolute comparisons break down in
+ degenerate cases. */
+ while (degree () > 0
+ && (fabs (coefs_.top ()) < FUDGE *fabs (coefs_.top (1))
+ || !coefs_.top ()))
coefs_.pop ();
}
-
-
void
-Polynomial::operator += (Polynomial const &p)
+Polynomial::operator+= (Polynomial const &p)
{
- while (degree () < p.degree())
+ while (degree () < p.degree ())
coefs_.push (0.0);
- for (int i = 0; i <= p.degree(); i++)
+ for (int i = 0; i <= p.degree (); i++)
coefs_[i] += p.coefs_[i];
}
-
void
-Polynomial::operator -= (Polynomial const &p)
+Polynomial::operator-= (Polynomial const &p)
{
- while (degree () < p.degree())
+ while (degree () < p.degree ())
coefs_.push (0.0);
- for (int i = 0; i <= p.degree(); i++)
+ for (int i = 0; i <= p.degree (); i++)
coefs_[i] -= p.coefs_[i];
}
-
void
Polynomial::scalarmultiply (Real fact)
{
coefs_[i] *= fact;
}
-
-
void
-Polynomial::set_negate (const Polynomial & src)
+Polynomial::set_negate (const Polynomial &src)
{
for (int i = 0; i <= src.degree (); i++)
coefs_[i] = -src.coefs_[i];
}
/// mod of #u/v#
-int
+int
Polynomial::set_mod (const Polynomial &u, const Polynomial &v)
{
- (*this) = u;
-
- if (v.lc () < 0.0) {
- for (int k = u.degree () - v.degree () - 1; k >= 0; k -= 2)
- coefs_[k] = -coefs_[k];
-
- for (int k = u.degree () - v.degree (); k >= 0; k--)
- for (int j = v.degree () + k - 1; j >= k; j--)
- coefs_[j] = -coefs_[j] - coefs_[v.degree () + k] * v.coefs_[j - k];
- } else {
- for (int k = u.degree () - v.degree (); k >= 0; k--)
- for (int j = v.degree () + k - 1; j >= k; j--)
- coefs_[j] -= coefs_[v.degree () + k] * v.coefs_[j - k];
- }
+ (*this) = u;
+
+ if (v.lc () < 0.0)
+ {
+ for (int k = u.degree () - v.degree () - 1; k >= 0; k -= 2)
+ coefs_[k] = -coefs_[k];
+
+ for (int k = u.degree () - v.degree (); k >= 0; k--)
+ for (int j = v.degree () + k - 1; j >= k; j--)
+ coefs_[j] = -coefs_[j] - coefs_[v.degree () + k] * v.coefs_[j - k];
+ }
+ else
+
+ {
+ for (int k = u.degree () - v.degree (); k >= 0; k--)
+ for (int j = v.degree () + k - 1; j >= k; j--)
+ coefs_[j] -= coefs_[v.degree () + k] * v.coefs_[j - k];
+ }
int k = v.degree () - 1;
while (k >= 0 && coefs_[k] == 0.0)
}
void
-Polynomial::check_sol (Real x) const
+Polynomial::check_sol (Real x) const
{
- Real f=eval (x);
+ Real f = eval (x);
Polynomial p (*this);
p.differentiate ();
Real d = p.eval (x);
-
- if ( abs (f) > abs (d) * FUDGE)
- ;
+
+ if (abs (f) > abs (d) * FUDGE);
/*
warning ("x=%f is not a root of polynomial\n"
"f (x)=%f, f' (x)=%f \n", x, f, d); */
}
-
+
void
Polynomial::check_sols (Array<Real> roots) const
{
- for (int i=0; i< roots.size (); i++)
+ for (int i = 0; i< roots.size (); i++)
check_sol (roots[i]);
}
inline Real cubic_root (Real x)
{
if (x > 0.0)
- return pow (x, 1.0/3.0) ;
+ return pow (x, 1.0 / 3.0);
else if (x < 0.0)
- return -pow (-x, 1.0/3.0);
+ return -pow (-x, 1.0 / 3.0);
else
return 0.0;
}
Polynomial::solve_cubic ()const
{
Array<Real> sol;
-
+
/* normal form: x^3 + Ax^2 + Bx + C = 0 */
Real A = coefs_[2] / coefs_[3];
Real B = coefs_[1] / coefs_[3];
* substitute x = y - A/3 to eliminate quadric term: x^3 +px + q = 0
*/
- Real sq_A = A * A;
+ Real sq_A = A *A;
Real p = 1.0 / 3 * (-1.0 / 3 * sq_A + B);
- Real q = 1.0 / 2 * (2.0 / 27 * A * sq_A - 1.0 / 3 * A * B + C);
+ Real q = 1.0 / 2 * (2.0 / 27 * A *sq_A - 1.0 / 3 * A *B + C);
/* use Cardano's formula */
Real cb = p * p * p;
Real D = q * q + cb;
- if (iszero (D)) {
- if (iszero (q)) { /* one triple solution */
- sol.push (0);
- sol.push (0);
- sol.push (0);
- } else { /* one single and one double solution */
- Real u = cubic_root (-q);
-
- sol.push (2 * u);
- sol.push (-u);
- }
- } else if (D < 0) { /* Casus irreducibilis: three real solutions */
+ if (iszero (D))
+ {
+ if (iszero (q)) { /* one triple solution */
+ sol.push (0);
+ sol.push (0);
+ sol.push (0);
+ } else { /* one single and one double solution */
+ Real u = cubic_root (-q);
+
+ sol.push (2 * u);
+ sol.push (-u);
+ }
+ } else if (D < 0) { /* Casus irreducibilis: three real solutions */
Real phi = 1.0 / 3 * acos (-q / sqrt (-cb));
Real t = 2 * sqrt (-p);
sol.push (t * cos (phi));
sol.push (-t * cos (phi + M_PI / 3));
- sol.push ( -t * cos (phi - M_PI / 3));
+ sol.push (-t * cos (phi - M_PI / 3));
} else { /* one real solution */
Real sqrt_D = sqrt (D);
Real u = cubic_root (sqrt_D - q);
Real v = -cubic_root (sqrt_D + q);
- sol.push ( u + v);
+ sol.push (u + v);
}
/* resubstitute */
sol[i] -= sub;
#ifdef PARANOID
- assert (fabs (eval (sol[i]) ) < 1e-8);
+ assert (fabs (eval (sol[i])) < 1e-8);
#endif
}
-
+
return sol;
}
return coefs_.top ();
}
-Real&
-Polynomial::lc ()
+Real &
+Polynomial::lc ()
{
return coefs_.top ();
}
return coefs_.size () -1;
}
/*
- all roots of quadratic eqn.
- */
+ all roots of quadratic eqn.
+*/
Array<Real>
Polynomial::solve_quadric ()const
{
Real D = p * p - q;
- if (D>0) {
- D = sqrt (D);
+ if (D > 0)
+ {
+ D = sqrt (D);
- sol.push ( D - p);
- sol.push ( -D - p);
- }
- return sol;
+ sol.push (D - p);
+ sol.push (-D - p);
+ }
+ return sol;
}
/* solve linear equation */
{
Array<Real> s;
if (coefs_[1])
- s.push ( -coefs_[0] / coefs_[1]);
+ s.push (-coefs_[0] / coefs_[1]);
return s;
}
-
Array<Real>
Polynomial::solve () const
{
- Polynomial * me = (Polynomial*) this;
+ Polynomial *me = (Polynomial *) this;
me->clean ();
-
+
switch (degree ())
{
case 1:
}
void
-Polynomial:: operator *= (Polynomial const &p2)
+Polynomial:: operator*= (Polynomial const &p2)
{
- *this = multiply (*this,p2);
-}
-
+ *this = multiply (*this, p2);
+}
projects / lilypond.git / blobdiff