"Fossies" - the Fresh Open Source Software Archive 
Member "mapm_4.9.5a/mapm_pow.c" (21 Feb 2010, 4338 Bytes) of package /linux/misc/old/mapm-4.9.5a.tar.gz:
As a special service "Fossies" has tried to format the requested source page into HTML format using (guessed) C and C++ source code syntax highlighting (style:
standard) with prefixed line numbers and
code folding option.
Alternatively you can here
view or
download the uninterpreted source code file.
For more information about "mapm_pow.c" see the
Fossies "Dox" file reference documentation.
1
2 /*
3 * M_APM - mapm_pow.c
4 *
5 * Copyright (C) 2000 - 2007 Michael C. Ring
6 *
7 * Permission to use, copy, and distribute this software and its
8 * documentation for any purpose with or without fee is hereby granted,
9 * provided that the above copyright notice appear in all copies and
10 * that both that copyright notice and this permission notice appear
11 * in supporting documentation.
12 *
13 * Permission to modify the software is granted. Permission to distribute
14 * the modified code is granted. Modifications are to be distributed by
15 * using the file 'license.txt' as a template to modify the file header.
16 * 'license.txt' is available in the official MAPM distribution.
17 *
18 * This software is provided "as is" without express or implied warranty.
19 */
20
21 /*
22 * $Id: mapm_pow.c,v 1.10 2007/12/03 01:46:07 mike Exp $
23 *
24 * This file contains the POW function.
25 *
26 * $Log: mapm_pow.c,v $
27 * Revision 1.10 2007/12/03 01:46:07 mike
28 * Update license
29 *
30 * Revision 1.9 2002/11/05 23:39:42 mike
31 * use new set_to_zero call
32 *
33 * Revision 1.8 2002/11/03 22:20:59 mike
34 * Updated function parameters to use the modern style
35 *
36 * Revision 1.7 2001/07/16 19:24:26 mike
37 * add function M_free_all_pow
38 *
39 * Revision 1.6 2000/09/05 22:15:03 mike
40 * minor tweak
41 *
42 * Revision 1.5 2000/08/22 21:22:29 mike
43 * if parameter yy is an integer, call the more
44 * efficient _integer_pow function
45 *
46 * Revision 1.4 2000/08/22 20:42:08 mike
47 * compute more digits in the log calculation
48 *
49 * Revision 1.3 2000/05/24 20:08:21 mike
50 * update some comments
51 *
52 * Revision 1.2 2000/05/23 23:20:11 mike
53 * return 1 when input is 0^0.
54 *
55 * Revision 1.1 2000/05/18 22:10:43 mike
56 * Initial revision
57 */
58
59 #include "m_apm_lc.h"
60
61 static M_APM M_last_xx_input;
62 static M_APM M_last_xx_log;
63 static int M_last_log_digits;
64 static int M_size_flag = 0;
65
66 /****************************************************************************/
67 void M_free_all_pow()
68 {
69 if (M_size_flag != 0)
70 {
71 m_apm_free(M_last_xx_input);
72 m_apm_free(M_last_xx_log);
73 M_size_flag = 0;
74 }
75 }
76 /****************************************************************************/
77 /*
78 Calculate the POW function by calling EXP :
79
80 Y A
81 X = e where A = Y * log(X)
82 */
83 void m_apm_pow(M_APM rr, int places, M_APM xx, M_APM yy)
84 {
85 int iflag, pflag;
86 char sbuf[64];
87 M_APM tmp8, tmp9;
88
89 /* if yy == 0, return 1 */
90
91 if (yy->m_apm_sign == 0)
92 {
93 m_apm_copy(rr, MM_One);
94 return;
95 }
96
97 /* if xx == 0, return 0 */
98
99 if (xx->m_apm_sign == 0)
100 {
101 M_set_to_zero(rr);
102 return;
103 }
104
105 if (M_size_flag == 0) /* init locals on first call */
106 {
107 M_size_flag = M_get_sizeof_int();
108 M_last_log_digits = 0;
109 M_last_xx_input = m_apm_init();
110 M_last_xx_log = m_apm_init();
111 }
112
113 /*
114 * if 'yy' is a small enough integer, call the more
115 * efficient _integer_pow function.
116 */
117
118 if (m_apm_is_integer(yy))
119 {
120 iflag = FALSE;
121
122 if (M_size_flag == 2) /* 16 bit compilers */
123 {
124 if (yy->m_apm_exponent <= 4)
125 iflag = TRUE;
126 }
127 else /* >= 32 bit compilers */
128 {
129 if (yy->m_apm_exponent <= 7)
130 iflag = TRUE;
131 }
132
133 if (iflag)
134 {
135 m_apm_to_integer_string(sbuf, yy);
136 m_apm_integer_pow(rr, places, xx, atoi(sbuf));
137 return;
138 }
139 }
140
141 tmp8 = M_get_stack_var();
142 tmp9 = M_get_stack_var();
143
144 /*
145 * If parameter 'X' is the same this call as it
146 * was the previous call, re-use the saved log
147 * calculation from last time.
148 */
149
150 pflag = FALSE;
151
152 if (M_last_log_digits >= places)
153 {
154 if (m_apm_compare(xx, M_last_xx_input) == 0)
155 pflag = TRUE;
156 }
157
158 if (pflag)
159 {
160 m_apm_round(tmp9, (places + 8), M_last_xx_log);
161 }
162 else
163 {
164 m_apm_log(tmp9, (places + 8), xx);
165
166 M_last_log_digits = places + 2;
167
168 /* save the 'X' input value and the log calculation */
169
170 m_apm_copy(M_last_xx_input, xx);
171 m_apm_copy(M_last_xx_log, tmp9);
172 }
173
174 m_apm_multiply(tmp8, tmp9, yy);
175 m_apm_exp(rr, places, tmp8);
176 M_restore_stack(2); /* restore the 2 locals we used here */
177 }
178 /****************************************************************************/