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- /* sys/ldfrexp.c
- *
- * Copyright (C) 2002, Gert Van den Eynde
- *
- * 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
- * the Free Software Foundation; either version 3 of the License, or (at
- * your option) any later version.
- *
- * This program 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 this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- */
- #include "gsl__config.h"
- #include <math.h>
- #include "gsl_math.h"
- double
- gsl_ldexp (const double x, const int e)
- {
- double p2 = pow (2.0, (double)e);
- return x * p2;
- }
- double
- gsl_frexp (const double x, int *e)
- {
- if (x == 0.0)
- {
- *e = 0;
- return 0.0;
- }
- else
- {
- double ex = ceil (log (fabs (x)) / M_LN2);
- int ei = (int) ex;
- double f = gsl_ldexp (x, -ei);
- while (fabs (f) >= 1.0)
- {
- ei++;
- f /= 2.0;
- }
-
- while (fabs (f) < 0.5)
- {
- ei--;
- f *= 2.0;
- }
- *e = ei;
- return f;
- }
- }
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