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[project @ 1993-08-08 01:20:23 by jwe] Initial revision
author jwe
date Sun, 08 Aug 1993 01:21:46 +0000
parents
children 380cb9ccc889
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2:c0190df9885d 3:9a4c07481e61
1 // Range.cc -*- C++ -*-
2 /*
3
4 Copyright (C) 1992, 1993 John W. Eaton
5
6 This file is part of Octave.
7
8 Octave is free software; you can redistribute it and/or modify it
9 under the terms of the GNU General Public License as published by the
10 Free Software Foundation; either version 2, or (at your option) any
11 later version.
12
13 Octave is distributed in the hope that it will be useful, but WITHOUT
14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
17
18 You should have received a copy of the GNU General Public License
19 along with Octave; see the file COPYING. If not, write to the Free
20 Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
21
22 */
23
24 #ifdef __GNUG__
25 #pragma implementation
26 #endif
27
28 #include <limits.h>
29
30 #include "Range.h"
31
32 void
33 Range::print_range (void)
34 {
35 cerr << "Range: _base = " << _base
36 << " _limit " << _limit
37 << " _inc " << _inc
38 << " _nelem " << _nelem << "\n";
39 }
40
41 ostream&
42 operator << (ostream& os, const Range& a)
43 {
44 double b = a.base ();
45 double increment = a.inc ();
46 int num_elem = a.nelem ();
47
48 for (int i = 0; i < num_elem; i++)
49 os << b + i * increment << " ";
50
51 os << "\n";
52
53 return os;
54 }
55
56 istream&
57 operator >> (istream& is, Range& a)
58 {
59 is >> a._base;
60 if (is)
61 {
62 is >> a._limit;
63 if (is)
64 {
65 is >> a._inc;
66 a._nelem = a.nelem_internal ();
67 }
68 }
69
70 return is;
71 }
72
73 int
74 Range::nelem_internal (void) const
75 {
76 // Find an approximate number of elements, then do the best we can to
77 // find the number of elements that we would get if we had done
78 // something like
79 //
80 // nelem = 0;
81 // while (base + nelem * inc <= limit)
82 // nelem++;
83 //
84 // (for limit > base && inc > 0)
85
86 double ntry = (_limit - _base) / _inc;
87 double max_val = (double) INT_MAX;
88
89 if (ntry > max_val)
90 return -1;
91
92 if (_limit > _base && _inc > 0)
93 {
94 // Our approximation may have been too big.
95
96 while (_base + ntry * _inc > _limit && ntry > 0)
97 ntry = ntry - 1;
98
99 // Now that we are close, get the actual number.
100
101 while (_base + ntry * _inc <= _limit && ntry <= max_val)
102 ntry = ntry + 1;
103 }
104 else if (_limit < _base && _inc < 0)
105 {
106 // Our approximation may have been too big.
107
108 while (_base + ntry * _inc < _limit && ntry > 0)
109 ntry = ntry - 1;
110
111 // Now that we are close, get the actual number.
112
113 while (_base + ntry * _inc >= _limit && ntry <= max_val)
114 ntry = ntry + 1;
115 }
116 else if (_limit == _base)
117 ntry = 1;
118 else
119 ntry = 0;
120
121 if (ntry > max_val)
122 return -1;
123 else
124 return (int) ntry;
125 }
126
127 /*
128 ;;; Local Variables: ***
129 ;;; mode: C++ ***
130 ;;; page-delimiter: "^/\\*" ***
131 ;;; End: ***
132 */