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authorLorry Tar Creator <lorry-tar-importer@baserock.org>2013-03-14 05:42:27 +0000
committer <>2013-04-03 16:25:08 +0000
commitc4dd7a1a684490673e25aaf4fabec5df138854c4 (patch)
tree4d57c44caae4480efff02b90b9be86f44bf25409 /ext/bcmath/libbcmath/src/raise.c
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+/* raise.c: bcmath library file. */
+/*
+ Copyright (C) 1991, 1992, 1993, 1994, 1997 Free Software Foundation, Inc.
+ Copyright (C) 2000 Philip A. Nelson
+
+ This library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2 of the License, or (at your option) any later version.
+
+ This library 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
+ Lesser General Public License for more details. (COPYING.LIB)
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with this library; if not, write to:
+
+ The Free Software Foundation, Inc.
+ 59 Temple Place, Suite 330
+ Boston, MA 02111-1307 USA.
+
+ You may contact the author by:
+ e-mail: philnelson@acm.org
+ us-mail: Philip A. Nelson
+ Computer Science Department, 9062
+ Western Washington University
+ Bellingham, WA 98226-9062
+
+*************************************************************************/
+
+#include <config.h>
+#include <stdio.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <stdarg.h>
+#include "bcmath.h"
+#include "private.h"
+
+
+/* Raise NUM1 to the NUM2 power. The result is placed in RESULT.
+ Maximum exponent is LONG_MAX. If a NUM2 is not an integer,
+ only the integer part is used. */
+
+void
+bc_raise (bc_num num1, bc_num num2, bc_num *result, int scale TSRMLS_DC)
+{
+ bc_num temp, power;
+ long exponent;
+ int rscale;
+ int pwrscale;
+ int calcscale;
+ char neg;
+
+ /* Check the exponent for scale digits and convert to a long. */
+ if (num2->n_scale != 0)
+ bc_rt_warn ("non-zero scale in exponent");
+ exponent = bc_num2long (num2);
+ if (exponent == 0 && (num2->n_len > 1 || num2->n_value[0] != 0))
+ bc_rt_error ("exponent too large in raise");
+
+ /* Special case if exponent is a zero. */
+ if (exponent == 0)
+ {
+ bc_free_num (result);
+ *result = bc_copy_num (BCG(_one_));
+ return;
+ }
+
+ /* Other initializations. */
+ if (exponent < 0)
+ {
+ neg = TRUE;
+ exponent = -exponent;
+ rscale = scale;
+ }
+ else
+ {
+ neg = FALSE;
+ rscale = MIN (num1->n_scale*exponent, MAX(scale, num1->n_scale));
+ }
+
+ /* Set initial value of temp. */
+ power = bc_copy_num (num1);
+ pwrscale = num1->n_scale;
+ while ((exponent & 1) == 0)
+ {
+ pwrscale = 2*pwrscale;
+ bc_multiply (power, power, &power, pwrscale TSRMLS_CC);
+ exponent = exponent >> 1;
+ }
+ temp = bc_copy_num (power);
+ calcscale = pwrscale;
+ exponent = exponent >> 1;
+
+ /* Do the calculation. */
+ while (exponent > 0)
+ {
+ pwrscale = 2*pwrscale;
+ bc_multiply (power, power, &power, pwrscale TSRMLS_CC);
+ if ((exponent & 1) == 1) {
+ calcscale = pwrscale + calcscale;
+ bc_multiply (temp, power, &temp, calcscale TSRMLS_CC);
+ }
+ exponent = exponent >> 1;
+ }
+
+ /* Assign the value. */
+ if (neg)
+ {
+ bc_divide (BCG(_one_), temp, result, rscale TSRMLS_CC);
+ bc_free_num (&temp);
+ }
+ else
+ {
+ bc_free_num (result);
+ *result = temp;
+ if ((*result)->n_scale > rscale)
+ (*result)->n_scale = rscale;
+ }
+ bc_free_num (&power);
+}
+