summaryrefslogtreecommitdiffstats
path: root/kbruch/src/ratio.cpp
blob: 0ba1e1c49db6b9dbd1ac4b746acbe45a51f51935 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
/***************************************************************************
                          ratio.cpp  -  source code of class ratio
                             -------------------
    begin                : Tue Nov 27 16:40:42 CET 2001
    copyright            : (C) 2001-2004 by Sebastian Stein
    email                : seb.kde@hpfsc.de
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   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 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#include <kdebug.h>

#include "ratio.h"
#include "primenumber.h"

/* ----- public member functions ----- */

/* constructor */
ratio::ratio(int pnumerator, int pdenominator):m_numerator(pnumerator), m_denominator(pdenominator)
{
#ifdef DEBUG
	kdDebug() << "constructor ratio" << endl;
#endif

	// denominator is never allowed to be 0
	if (!m_denominator)
		m_denominator = 1;

	// reduce the new ratio
	reduce();
}

/* copy constructor */
ratio::ratio(const ratio & copy_ratio)
{
#ifdef DEBUG
	kdDebug() << "copy constructor ratio" << endl;
#endif

	setNumerator(copy_ratio.numerator(), false);
	setDenominator(copy_ratio.denominator(), false);
}

/* destructor */
ratio::~ratio()
{
#ifdef DEBUG
	kdDebug() << "destructor ratio" << endl;
#endif
}

/* displays the ratio on stdout; just for debugging */
TQTextStream & ratio::display(TQTextStream & str) const
{
	int tmp_width = str.width();
	str << qSetW(5) << " ";
	str << qSetW(5) << m_numerator << endl;
	str << qSetW(tmp_width) << " ";
	str << " ----- " << endl;
	str << qSetW(tmp_width) << " ";
	return str << qSetW(5) << m_denominator;
}

/* return the numerator */
int ratio::numerator() const
{
	return m_numerator;
}

/* return the denominator */
int ratio::denominator() const
{
	return m_denominator;
}

/* set the numerator */
void ratio::setNumerator(int pnumerator, bool reduce_it)
{
	m_numerator = pnumerator;

	// check, if we have to reduce the ratio
	if (reduce_it == true)
		reduce();

	return;
}

/* set the denominator */
void ratio::setDenominator(int pdenominator, bool reduce_it)
{
	/* denominator is not allowed to be 0 */
	if (!pdenominator)
		pdenominator = 1;

	m_denominator = pdenominator;

	// check, if we have to reduce the ratio
	if (reduce_it == true)
		reduce();

	return;
}

/* add a ratio to a ratio like c = a + b */
ratio ratio::operator+(ratio addend)
{
	// this object will be returned as the sum
	ratio sum(0, 1);

	// calculate and set the numerator without reducing
	sum.setNumerator(m_numerator * addend.denominator()
                  + addend.numerator() * m_denominator, false);

	// calculate and set the denominator without reducing
	sum.setDenominator(m_denominator * addend.denominator(), false);

	// reduce the sum
	sum.reduce();

	return sum;
}

/* sub a ratio from a ratio like c = a - b */
ratio ratio::operator-(ratio subtrahend)
{
	/* this object will be returned as the difference */
	ratio diff(0, 1);

	/* change the sign of the subtrahend, so we can handle it as an addition */
	subtrahend.change_sign();
	diff = operator+(subtrahend);

	/* we have to change the sign back, so everything will be as before */
	subtrahend.change_sign();

	/* return the difference */
	return diff;
}

/* mul a ratio with a ratio like c = a * b */
ratio ratio::operator*(ratio factor)
{
	// this object will be returned as the product
	ratio product(0, 1);

	// calculate and set numerator and denominator without reducing
	product.setNumerator(m_numerator * factor.numerator(), false);
	product.setDenominator(m_denominator * factor.denominator(), false);

	// reduce the product
	product.reduce();

	return product;
}

/* div a ratio with a ratio like c = a / b */
ratio ratio::operator/(ratio divisor)
{
	/* this object will be returned as the quotient */
	ratio quotient(0, 1);

	/* exchange numerator and denominator so we can handle as multiplication */
	divisor.reziproc();
	quotient = operator*(divisor);

	/* go back to the original state */
	divisor.reziproc();

	return quotient;
}

/* we need this for initialization during a function prototyp;
 * ratio fraction = 0 */
ratio ratio::operator=(int dummy)
{
	m_numerator = dummy;
	m_denominator = 1;

	return *this;
}

/* check, if the ratios are equivalent; -1/2 == 1/-2 -> TRUE */
bool ratio::operator==(ratio right)
{
	signed short orig_sign = 1, right_sign = 1;

	/* we do not check the presign at this point */
	if (TQABS(m_numerator) != TQABS(right.numerator()))
		return false;
	if (TQABS(m_denominator) != TQABS(right.denominator()))
		return false;

	/* check if the signs of the ratios are equivalent */
	if (m_numerator < 0)
		orig_sign = -1;
	if (m_denominator < 0)
		orig_sign *= -1;
	if (right.numerator() < 0)
		right_sign = -1;
	if (right.denominator() < 0)
		right_sign *= -1;

	if (orig_sign != right_sign)
		return false;

	return true;
}

bool ratio::operator<(ratio right)
{
	signed short sign = 1;
	ratio tmp_ratio = ratio(m_numerator, m_denominator) - right;

	// check for this == right
	if (tmp_ratio == ratio(0, 1))
		return false;

	// get the presign of the diff
	if (tmp_ratio.numerator() < 0)
		sign = -1;
	if (tmp_ratio.denominator() < 0)
		sign *= -1;

	// if the diff is negative, this is smaller then right
	if (sign > 0)
	{
		return false;
	} else {
		return true;
	}
}

bool ratio::operator>(ratio right)
{
	signed short sign = 1;
	ratio tmp_ratio = ratio(m_numerator, m_denominator) - right;

	// check for this == right
	if (tmp_ratio == ratio(0, 1))
		return false;

	// get the presign of the diff
	if (tmp_ratio.numerator() < 0)
		sign = -1;
	if (tmp_ratio.denominator() < 0)
		sign *= -1;

	// if the diff is positive, this is smaller then right
	if (sign < 0)
	{
		return false;
	} else {
		return true;
	}
}

/* ----- private member functions ----- */

/* reduce the ratio */
void ratio::reduce()
{
	/* we try prime numbers as divisors; I think it is the fastet way to do */
	primenumber number;
	short sign_numerator = 0, sign_denominator = 0;

	/* make the whole ratio positive; save the signs; it is easier to reduce
	 * the ratio, if it is positive */
	if (m_numerator < 0) // save numerator sign
	{
		sign_numerator = 1;
		m_numerator *= -1;
	}
	if (m_denominator < 0) // save denominator sign
	{
		sign_denominator = 1;
		m_denominator *= -1;
	}

	for (int divisor = number.get_first();
	        divisor <= m_numerator && divisor <= m_denominator; divisor = number.get_next())
	{
		if (divisor == 0)
		{
#ifdef DEBUG
			kdDebug() << "ratio::reduce() -> divisor == 0 !!!" << endl;
			kdDebug() << "m_numerator: " << m_numerator << endl;
			kdDebug() << "m_denominator: " << m_denominator << endl;
			// cin.get();
#endif
			/* so that the application does not crash with a floating
			 * point exception; the error should not appear, but in some
			 * cases it does and I do not know why */
			continue;
		}

		/* is the prime number a divisor of numerator and denominator? */
		if ((m_numerator % divisor == 0) && (m_denominator % divisor == 0))
		{
			/* reduce the ratio by the divisor */
			m_numerator /= divisor;
			m_denominator /= divisor;

			/* we have to go recursive, if the 2 is a divisor, because there
			 * is no way to step one number before 2 -> there is no prime
			 * number smaller than 2 */
			if (divisor == 2)
				reduce();
			else
				number.move_back(); // the prime number could be a divisor again
		} // if ((zaehler % divisor == 0) && (nenner % divisor == 0))
	} // for (unsigned int divisor = number.get_first(); ...

	/* restore the correct signs */
	if (sign_numerator)
		m_numerator *= -1;
	if (sign_denominator)
		m_denominator *= -1;
	if (m_numerator == 0)
		m_denominator = 1;

	return;
}

/* exchange numerator and denominator */
void ratio::reziproc()
{
	int temp = m_numerator;
	m_numerator = m_denominator;
	m_denominator = temp;

	return;
}


/* ------ private member functions ------ */

/* change the sign of the ratio; ratio = ratio * -1 */
void ratio::change_sign()
{
	/* this would be enough to change the sign of the ratio */
	m_numerator *= -1;

	/* if numerator and denominator both are negative, make them positive;
	 * if denominator is negative and numerator positive, exchange the sign */
	if ((m_numerator < 0 && m_denominator < 0) || (m_numerator > 0 && m_denominator < 0))
	{
		m_numerator *= -1;
		m_denominator *= -1;
	}

	return;
}


/* ------ some prototyps of non class functions ------ */

// it is possible to stram ratio_object
TQTextStream & operator<<(TQTextStream & str, const ratio & pratio)
{
	return pratio.display(str);
}