From ff18d7f21003a092361ab3428eb89b1414905e12 Mon Sep 17 00:00:00 2001
From: Sven Verdoolaege <skimo@kotnet.org>
Date: Wed, 10 Oct 2007 16:56:05 +0200
Subject: [PATCH] icounter: don't bother "normalizing" the exponents in the
 denominator

We used to make sure these exponents are positive, but there
is no need to do that on full specialization.
See also d566b49a2da75b61fb9a310dcdc1cbe41a7e1cad.
---
 dpoly.cc   |  6 ++++++
 reducer.cc | 24 ++----------------------
 reducer.h  |  2 --
 3 files changed, 8 insertions(+), 24 deletions(-)

diff --git a/dpoly.cc b/dpoly.cc
index 1249cee..22150dd 100644
--- a/dpoly.cc
+++ b/dpoly.cc
@@ -67,6 +67,12 @@ Vector *dpoly::div(const dpoly& d)
     Vector *denom = Vector_Alloc(len);
     Value tmp;
     value_init(tmp);
+
+    /* Make sure denominators are positive */
+    if (value_neg_p(d.coeff->p[0])) {
+	Vector_Oppose(d.coeff->p, d.coeff->p, d.coeff->Size);
+	Vector_Oppose(coeff->p, coeff->p, coeff->Size);
+    }
     value_assign(denom->p[0], d.coeff->p[0]);
     for (int i = 1; i < len; ++i) {
 	value_multiply(denom->p[i], denom->p[i-1], denom->p[0]);
diff --git a/reducer.cc b/reducer.cc
index 51b0a31..7d8071a 100644
--- a/reducer.cc
+++ b/reducer.cc
@@ -423,24 +423,6 @@ void split_one(const mat_ZZ& num, vec_ZZ& num_s, mat_ZZ& num_p,
     }
 }
 
-void normalize(ZZ& sign, ZZ& num, vec_ZZ& den)
-{
-    unsigned dim = den.length();
-
-    int change = 0;
-
-    for (int j = 0; j < den.length(); ++j) {
-	if (den[j] > 0)
-	    change ^= 1;
-	else {
-	    den[j] = abs(den[j]);
-	    num += den[j];
-	}
-    }
-    if (change)
-	sign = -sign;
-}
-
 void icounter::base(const QQ& c, const vec_ZZ& num, const mat_ZZ& den_f)
 {
     int r;
@@ -451,8 +433,7 @@ void icounter::base(const QQ& c, const vec_ZZ& num, const mat_ZZ& den_f)
     ZZ num_s = num[0];
     for (r = 0; r < len; ++r)
 	den_s[r] = den_f[r][0];
-    ZZ sign = ZZ(INIT_VAL, 1);
-    normalize(sign, num_s, den_s);
+    int sign = (len % 2) ? -1 : 1;
 
     zz2value(num_s, tz);
     dpoly n(len, tz);
@@ -486,8 +467,7 @@ void infinite_icounter::base(const QQ& c, const vec_ZZ& num, const mat_ZZ& den_f
 
     for (r = 0; r < len; ++r)
 	den_s[r] = den_f[r][0];
-    ZZ sign = ZZ(INIT_VAL, 1);
-    normalize(sign, num_s, den_s);
+    int sign = (len % 2) ? -1 : 1;
 
     zz2value(num_s, tz);
     dpoly n(len, tz);
diff --git a/reducer.h b/reducer.h
index ad70273..9e01bce 100644
--- a/reducer.h
+++ b/reducer.h
@@ -127,8 +127,6 @@ struct icounter : public ireducer {
     }
 };
 
-void normalize(ZZ& sign, ZZ& num, vec_ZZ& den);
-
 /* An incremental counter for possibly infinite sets.
  * Rather than just keeping track of the constant term
  * of the Laurent expansions, we also keep track of the
-- 
2.11.4.GIT