simplex-glpk with modified glpk for fpgaHEADmaster

1 files changed, 62 insertions, 0 deletions

diff --git a/glpk-5.0/src/misc/round2n.c b/glpk-5.0/src/misc/round2n.c
new file mode 100644
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+++ b/glpk-5.0/src/misc/round2n.c
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+/* round2n.c (round floating-point number to nearest power of two) */
+
+/***********************************************************************
+*  This code is part of GLPK (GNU Linear Programming Kit).
+*  Copyright (C) 2000 Free Software Foundation, Inc.
+*  Written by Andrew Makhorin <mao@gnu.org>.
+*
+*  GLPK 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.
+*
+*  GLPK 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 GLPK. If not, see <http://www.gnu.org/licenses/>.
+***********************************************************************/
+
+#include "env.h"
+#include "misc.h"
+
+/***********************************************************************
+*  NAME
+*
+*  round2n - round floating-point number to nearest power of two
+*
+*  SYNOPSIS
+*
+*  #include "misc.h"
+*  double round2n(double x);
+*
+*  RETURNS
+*
+*  Given a positive floating-point value x the routine round2n returns
+*  2^n such that |x - 2^n| is minimal.
+*
+*  EXAMPLES
+*
+*  round2n(10.1) = 2^3 = 8
+*  round2n(15.3) = 2^4 = 16
+*  round2n(0.01) = 2^(-7) = 0.0078125
+*
+*  BACKGROUND
+*
+*  Let x = f * 2^e, where 0.5 <= f < 1 is a normalized fractional part,
+*  e is an integer exponent. Then, obviously, 0.5 * 2^e <= x < 2^e, so
+*  if x - 0.5 * 2^e <= 2^e - x, we choose 0.5 * 2^e = 2^(e-1), and 2^e
+*  otherwise. The latter condition can be written as 2 * x <= 1.5 * 2^e
+*  or 2 * f * 2^e <= 1.5 * 2^e or, finally, f <= 0.75. */
+
+double round2n(double x)
+{     int e;
+      double f;
+      xassert(x > 0.0);
+      f = frexp(x, &e);
+      return ldexp(1.0, f <= 0.75 ? e-1 : e);
+}
+
+/* eof */