1 /*
2 SPDX-FileCopyrightText: 2016 Akarsh Simha <akarsh.simha@kdemail.net>
3
4 SPDX-License-Identifier: GPL-2.0-or-later
5 */
6
7 /* Project Includes */
8 #include "cachingdms.h"
9
10 /* KDE Includes */
11
12 /* Qt Includes */
13 #include <QString>
14
15 /* STL Includes */
16 #include <cmath>
17
18 #ifdef COUNT_DMS_SINCOS_CALLS
19 unsigned long CachingDms::cachingdms_constructor_calls = 0;
20 long CachingDms::cachingdms_delta = 0; // difference of ( trig function calls ) - ( trig computations )
21 unsigned long CachingDms::cachingdms_bad_uses = 0;
22 #endif
23
CachingDms(const double & x)24 CachingDms::CachingDms(const double &x) : dms(x)
25 {
26 dms::SinCos(m_sin, m_cos);
27 #ifdef COUNT_DMS_SINCOS_CALLS
28 ++cachingdms_constructor_calls;
29 cachingdms_delta -= 2;
30 m_cacheUsed = false;
31 #endif
32 }
33
34 #ifdef COUNT_DMS_SINCOS_CALLS
~CachingDms()35 CachingDms::~CachingDms()
36 {
37 if (!m_cacheUsed)
38 ++cachingdms_bad_uses;
39 }
40 #endif
41
CachingDms(const QString & s,bool isDeg)42 CachingDms::CachingDms(const QString &s, bool isDeg) : dms(s, isDeg)
43 {
44 dms::SinCos(m_sin, m_cos);
45 #ifdef COUNT_DMS_SINCOS_CALLS
46 ++cachingdms_constructor_calls;
47 cachingdms_delta -= 2;
48 m_cacheUsed = false;
49 #endif
50 }
51
CachingDms(const int & d,const int & m,const int & s,const int & ms)52 CachingDms::CachingDms(const int &d, const int &m, const int &s, const int &ms) : dms(d, m, s, ms)
53 {
54 dms::SinCos(m_sin, m_cos);
55 #ifdef COUNT_DMS_SINCOS_CALLS
56 ++cachingdms_constructor_calls;
57 cachingdms_delta -= 2;
58 m_cacheUsed = false;
59 #endif
60 }
61
setUsing_atan2(const double & y,const double & x)62 void CachingDms::setUsing_atan2(const double &y, const double &x)
63 {
64 /*
65 * NOTE: A bit of independent profiling shows that on my machine
66 * (Intel Core i5, x86_64, glibc 2.24-2) the square-root based
67 * computation below has some advantage, running ~ 70% faster on
68 * average for some range of values.
69 *
70 */
71 dms::setRadians(atan2(y, x));
72 double r = sqrt(y * y + x * x);
73 m_cos = x / r;
74 m_sin = y / r;
75
76 #ifdef COUNT_DMS_SINCOS_CALLS
77 if (!m_cacheUsed)
78 ++cachingdms_bad_uses;
79 m_cacheUsed = false;
80 #endif
81 // One may be tempted to do the following:
82 // dms::setRadians( atan2( y, x ) );
83 // m_cos = dms::cos();
84 // m_sin = (y/x) * m_cos;
85 // However, this has a problem when x = 0. The result for m_sin
86 // must be 1, but instead the above code will result in NaN.
87 // So we will need a conditional:
88 // m_sin = (x == 0) ? 1. : (y/x) * m_cos;
89 // The conditional makes the performance worse than just setting
90 // the angle and using sincos()
91 }
92
setUsing_asin(const double & sine)93 void CachingDms::setUsing_asin(const double &sine)
94 {
95 dms::setRadians(asin(sine));
96 m_sin = sine;
97 // Note: The below is valid because in the range of asin, which is
98 // [-pi/2, pi/2], cosine is always non-negative
99 m_cos = std::sqrt(1 - sine * sine);
100 #ifdef COUNT_DMS_SINCOS_CALLS
101 if (!m_cacheUsed)
102 ++cachingdms_bad_uses;
103 m_cacheUsed = false;
104 #endif
105 }
106
setUsing_acos(const double & cosine)107 void CachingDms::setUsing_acos(const double &cosine)
108 {
109 dms::setRadians(acos(cosine));
110 m_cos = cosine;
111 // Note: The below is valid because in the range of acos, which is
112 // [0, pi], sine is always non-negative
113 m_sin = std::sqrt(1 - cosine * cosine);
114 #ifdef COUNT_DMS_SINCOS_CALLS
115 if (!m_cacheUsed)
116 ++cachingdms_bad_uses;
117 m_cacheUsed = false;
118 #endif
119 }
120
fromString(const QString & s,bool deg)121 CachingDms CachingDms::fromString(const QString &s, bool deg)
122 {
123 CachingDms result;
124 result.setFromString(s, deg);
125 return result;
126 }
127
operator -()128 CachingDms CachingDms::operator-()
129 {
130 return CachingDms(-D, -m_sin, m_cos);
131 }
132
CachingDms(const dms & angle)133 CachingDms::CachingDms(const dms &angle)
134 {
135 D = angle.Degrees();
136 dms::SinCos(m_sin, m_cos);
137 #ifdef COUNT_DMS_SINCOS_CALLS
138 ++cachingdms_constructor_calls;
139 cachingdms_delta -= 2;
140 m_cacheUsed = false;
141 #endif
142 }
143
144 #ifdef COUNT_DMS_SINCOS_CALLS
CachingDms(const CachingDms & o)145 CachingDms::CachingDms(const CachingDms &o)
146 {
147 m_sin = o.sin();
148 m_cos = o.cos();
149 D = o.D;
150 m_cacheUsed = false;
151 }
operator =(const CachingDms & o)152 CachingDms &CachingDms::operator=(const CachingDms &o)
153 {
154 if (!m_cacheUsed)
155 ++cachingdms_bad_uses;
156 m_sin = o.sin();
157 m_cos = o.cos();
158 D = o.D;
159 m_cacheUsed = false;
160 return (*this);
161 }
162 #endif
163
164 // Makes trig identities more readable:
165 #define sinA a.sin()
166 #define cosA a.cos()
167 #define sinB b.sin()
168 #define cosB b.cos()
169
170 // We use trigonometric addition / subtraction formulae to speed up
171 // computation. This way, we have no trigonometric function calls at
172 // all, but only floating point multiplications and
173 // addition/subtraction instead.
174 // The only caveat is that error can accumulate if used repeatedly!
175
operator +(const CachingDms & a,const CachingDms & b)176 CachingDms operator+(const CachingDms &a, const CachingDms &b)
177 {
178 return CachingDms(a.Degrees() + b.Degrees(), sinA * cosB + cosA * sinB, cosA * cosB - sinA * sinB);
179 }
180
operator -(const CachingDms & a,const CachingDms & b)181 CachingDms operator-(const CachingDms &a, const CachingDms &b)
182 {
183 return CachingDms(a.Degrees() - b.Degrees(), sinA * cosB - cosA * sinB, cosA * cosB + sinA * sinB);
184 }
185
operator +(const dms & a,const CachingDms & b)186 CachingDms operator+(const dms &a, const CachingDms &b)
187 {
188 return CachingDms(a + dms(b));
189 }
190
operator -(const dms & a,const CachingDms & b)191 CachingDms operator-(const dms &a, const CachingDms &b)
192 {
193 return CachingDms(a - dms(b));
194 }
195
operator +(const CachingDms & a,const dms & b)196 CachingDms operator+(const CachingDms &a, const dms &b)
197 {
198 return CachingDms(dms(a) + b);
199 }
200
operator -(const CachingDms & a,const dms & b)201 CachingDms operator-(const CachingDms &a, const dms &b)
202 {
203 return CachingDms(dms(a) - b);
204 }
205
206 #undef sinA
207 #undef cosA
208 #undef sinB
209 #undef cosB
210