X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=blobdiff_plain;f=ginac%2Fpolynomial%2Fremainder.h;h=5e82149825a027bf6f3ea185e9ce51be11deb5e5;hp=c099dfe9f9d4b7caabf33f455390d860b121145d;hb=8cffcdf13d817a47f217f1a1043317d95969e070;hpb=1602530f716ba1d425a0667b897182b99c374823

diff --git a/ginac/polynomial/remainder.h b/ginac/polynomial/remainder.h
index c099dfe9..5e821498 100644
--- a/ginac/polynomial/remainder.h
+++ b/ginac/polynomial/remainder.h
@@ -3,7 +3,7 @@
  *  Functions calculating remainders. */
 
 /*
- *  GiNaC Copyright (C) 1999-2009 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2019 Johannes Gutenberg University Mainz, Germany
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -30,62 +30,7 @@
 
 namespace GiNaC {
 
-/**
- * @brief Polynomial remainder for univariate polynomials over fields
- *
- * Given two univariate polynomials \f$a, b \in F[x]\f$, where F is
- * a finite field (presumably Z/p) computes the remainder @a r, which is
- * defined as \f$a = b q + r\f$. Returns true if the remainder is zero
- * and false otherwise.
- */
-static bool
-remainder_in_field(umodpoly& r, const umodpoly& a, const umodpoly& b)
-{
-	typedef cln::cl_MI field_t;
-
-	if (degree(a) < degree(b)) {
-		r = a;
-		return false;
-	}
-	// The coefficient ring is a field, so any 0 degree polynomial
-	// divides any other polynomial.
-	if (degree(b) == 0) {
-		r.clear();
-		return true;
-	}
-
-	r = a;
-	const field_t b_lcoeff = lcoeff(b);
-	for (std::size_t k = a.size(); k-- >= b.size(); ) {
-
-		// r -= r_k/b_n x^{k - n} b(x)
-		if (zerop(r[k]))
-			continue;
-
-		field_t qk = div(r[k], b_lcoeff);
-		bug_on(zerop(qk), "division in a field yield zero: "
-			           << r[k] << '/' << b_lcoeff);
-
-		// Why C++ is so off-by-one prone?
-		for (std::size_t j = k, i = b.size(); i-- != 0; --j) {
-			if (zerop(b[i]))
-				continue;
-			r[j] = r[j] - qk*b[i];
-		}
-		bug_on(!zerop(r[k]), "polynomial division in field failed: " <<
-			              "r[" << k << "] = " << r[k] << ", " <<
-				      "r = " << r << ", b = " << b);
-
-	}
-
-	// Canonicalize the remainder: remove leading zeros. Give a hint
-	// to canonicalize(): we know degree(remainder) < degree(b) 
-	// (because the coefficient ring is a field), so 
-	// c_{degree(b)} \ldots c_{degree(a)} are definitely zero.
-	std::size_t from = degree(b) - 1;
-	canonicalize(r, from);
-	return r.empty();
-}
+bool remainder_in_field(umodpoly& r, const umodpoly& a, const umodpoly& b);
 
 /**
  * @brief Polynomial remainder for univariate polynomials over a ring.