a27d4bfcee4512c1a58b3a4a4cffdd43d021dde7
1 /*
2 * sbasis.h - S-power basis function class
3 *
4 * Authors:
5 * Nathan Hurst <njh@mail.csse.monash.edu.au>
6 * Michael Sloan <mgsloan@gmail.com>
7 *
8 * Copyright (C) 2006-2007 authors
9 *
10 * This library is free software; you can redistribute it and/or
11 * modify it either under the terms of the GNU Lesser General Public
12 * License version 2.1 as published by the Free Software Foundation
13 * (the "LGPL") or, at your option, under the terms of the Mozilla
14 * Public License Version 1.1 (the "MPL"). If you do not alter this
15 * notice, a recipient may use your version of this file under either
16 * the MPL or the LGPL.
17 *
18 * You should have received a copy of the LGPL along with this library
19 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 * You should have received a copy of the MPL along with this library
22 * in the file COPYING-MPL-1.1
23 *
24 * The contents of this file are subject to the Mozilla Public License
25 * Version 1.1 (the "License"); you may not use this file except in
26 * compliance with the License. You may obtain a copy of the License at
27 * http://www.mozilla.org/MPL/
28 *
29 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
30 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
31 * the specific language governing rights and limitations.
32 */
34 #ifndef SEEN_SBASIS_H
35 #define SEEN_SBASIS_H
36 #include <vector>
37 #include <cassert>
38 #include <iostream>
40 #include "linear.h"
41 #include "interval.h"
43 namespace Geom {
45 /*** An empty SBasis is identically 0. */
46 class SBasis : public std::vector<Linear>{
47 public:
48 SBasis() {}
49 explicit SBasis(double a) {
50 push_back(Linear(a,a));
51 }
52 SBasis(SBasis const & a) :
53 std::vector<Linear>(a)
54 {}
55 SBasis(Linear const & bo) {
56 push_back(bo);
57 }
59 //IMPL: FragmentConcept
60 typedef double output_type;
61 inline bool isZero() const {
62 if(empty()) return true;
63 for(unsigned i = 0; i < size(); i++) {
64 if(!(*this)[i].isZero()) return false;
65 }
66 return true;
67 }
68 bool isFinite() const;
69 inline double at0() const {
70 if(empty()) return 0; else return (*this)[0][0];
71 }
72 inline double at1() const{
73 if(empty()) return 0; else return (*this)[0][1];
74 }
76 double valueAt(double t) const {
77 double s = t*(1-t);
78 double p0 = 0, p1 = 0;
79 double sk = 1;
80 //TODO: rewrite as horner
81 for(unsigned k = 0; k < size(); k++) {
82 p0 += sk*(*this)[k][0];
83 p1 += sk*(*this)[k][1];
84 sk *= s;
85 }
86 return (1-t)*p0 + t*p1;
87 }
88 double operator()(double t) const {
89 return valueAt(t);
90 }
91 SBasis toSBasis() const { return SBasis(*this); }
93 double tailError(unsigned tail) const;
95 // compute f(g)
96 SBasis operator()(SBasis const & g) const;
98 Linear operator[](unsigned i) const {
99 assert(i < size());
100 return std::vector<Linear>::operator[](i);
101 }
103 //MUTATOR PRISON
104 Linear& operator[](unsigned i) { return this->at(i); }
106 //remove extra zeros
107 void normalize() {
108 while(!empty() && 0 == back()[0] && 0 == back()[1])
109 pop_back();
110 }
111 void truncate(unsigned k) { if(k < size()) resize(k); }
112 };
114 //TODO: figure out how to stick this in linear, while not adding an sbasis dep
115 inline SBasis Linear::toSBasis() const { return SBasis(*this); }
117 //implemented in sbasis-roots.cpp
118 Interval bounds_exact(SBasis const &a);
119 Interval bounds_fast(SBasis const &a, int order = 0);
120 Interval bounds_local(SBasis const &a, const Interval &t, int order = 0);
122 inline SBasis reverse(SBasis const &a) {
123 SBasis result;
124 result.reserve(a.size());
125 for(unsigned k = 0; k < a.size(); k++)
126 result.push_back(reverse(a[k]));
127 return result;
128 }
130 //IMPL: ScalableConcept
131 inline SBasis operator-(const SBasis& p) {
132 if(p.isZero()) return SBasis();
133 SBasis result;
134 result.reserve(p.size());
136 for(unsigned i = 0; i < p.size(); i++) {
137 result.push_back(-p[i]);
138 }
139 return result;
140 }
141 SBasis operator*(SBasis const &a, double k);
142 inline SBasis operator*(double k, SBasis const &a) { return a*k; }
143 inline SBasis operator/(SBasis const &a, double k) { return a*(1./k); }
144 SBasis& operator*=(SBasis& a, double b);
145 inline SBasis& operator/=(SBasis& a, double b) { return (a*=(1./b)); }
147 //IMPL: AddableConcept
148 SBasis operator+(const SBasis& a, const SBasis& b);
149 SBasis operator-(const SBasis& a, const SBasis& b);
150 SBasis& operator+=(SBasis& a, const SBasis& b);
151 SBasis& operator-=(SBasis& a, const SBasis& b);
153 //TODO: remove?
154 inline SBasis operator+(const SBasis & a, Linear const & b) {
155 if(b.isZero()) return a;
156 if(a.isZero()) return b;
157 SBasis result(a);
158 result[0] += b;
159 return result;
160 }
161 inline SBasis operator-(const SBasis & a, Linear const & b) {
162 if(b.isZero()) return a;
163 SBasis result(a);
164 result[0] -= b;
165 return result;
166 }
167 inline SBasis& operator+=(SBasis& a, const Linear& b) {
168 if(a.isZero())
169 a.push_back(b);
170 else
171 a[0] += b;
172 return a;
173 }
174 inline SBasis& operator-=(SBasis& a, const Linear& b) {
175 if(a.isZero())
176 a.push_back(-b);
177 else
178 a[0] -= b;
179 return a;
180 }
182 //IMPL: OffsetableConcept
183 inline SBasis operator+(const SBasis & a, double b) {
184 if(a.isZero()) return Linear(b, b);
185 SBasis result(a);
186 result[0] += b;
187 return result;
188 }
189 inline SBasis operator-(const SBasis & a, double b) {
190 if(a.isZero()) return Linear(-b, -b);
191 SBasis result(a);
192 result[0] -= b;
193 return result;
194 }
195 inline SBasis& operator+=(SBasis& a, double b) {
196 if(a.isZero())
197 a.push_back(Linear(b,b));
198 else
199 a[0] += b;
200 return a;
201 }
202 inline SBasis& operator-=(SBasis& a, double b) {
203 if(a.isZero())
204 a.push_back(Linear(-b,-b));
205 else
206 a[0] -= b;
207 return a;
208 }
210 SBasis shift(SBasis const &a, int sh);
211 SBasis shift(Linear const &a, int sh);
213 inline SBasis truncate(SBasis const &a, unsigned terms) {
214 SBasis c;
215 c.insert(c.begin(), a.begin(), a.begin() + std::min(terms, (unsigned)a.size()));
216 return c;
217 }
219 SBasis multiply(SBasis const &a, SBasis const &b);
221 SBasis integral(SBasis const &c);
222 SBasis derivative(SBasis const &a);
224 SBasis sqrt(SBasis const &a, int k);
226 // return a kth order approx to 1/a)
227 SBasis reciprocal(Linear const &a, int k);
228 SBasis divide(SBasis const &a, SBasis const &b, int k);
230 inline SBasis operator*(SBasis const & a, SBasis const & b) {
231 return multiply(a, b);
232 }
234 inline SBasis& operator*=(SBasis& a, SBasis const & b) {
235 a = multiply(a, b);
236 return a;
237 }
239 //valuation: degree of the first non zero coefficient.
240 inline unsigned
241 valuation(SBasis const &a, double tol=0){
242 unsigned val=0;
243 while( val<a.size() &&
244 fabs(a[val][0])<tol &&
245 fabs(a[val][1])<tol )
246 val++;
247 return val;
248 }
250 // a(b(t))
251 SBasis compose(SBasis const &a, SBasis const &b);
252 SBasis compose(SBasis const &a, SBasis const &b, unsigned k);
253 SBasis inverse(SBasis a, int k);
254 //compose_inverse(f,g)=compose(f,inverse(g)), but is numerically more stable in some good cases...
255 //TODO: requires g(0)=0 & g(1)=1 atm. generalization should be obvious.
256 SBasis compose_inverse(SBasis const &f, SBasis const &g, unsigned order=2, double tol=1e-3);
258 inline SBasis portion(const SBasis &t, double from, double to) { return compose(t, Linear(from, to)); }
260 // compute f(g)
261 inline SBasis
262 SBasis::operator()(SBasis const & g) const {
263 return compose(*this, g);
264 }
266 inline std::ostream &operator<< (std::ostream &out_file, const Linear &bo) {
267 out_file << "{" << bo[0] << ", " << bo[1] << "}";
268 return out_file;
269 }
271 inline std::ostream &operator<< (std::ostream &out_file, const SBasis & p) {
272 for(unsigned i = 0; i < p.size(); i++) {
273 out_file << p[i] << "s^" << i << " + ";
274 }
275 return out_file;
276 }
278 SBasis sin(Linear bo, int k);
279 SBasis cos(Linear bo, int k);
281 std::vector<double> roots(SBasis const & s);
282 std::vector<std::vector<double> > multi_roots(SBasis const &f,
283 std::vector<double> const &levels,
284 double htol=1e-7,
285 double vtol=1e-7,
286 double a=0,
287 double b=1);
289 }
291 /*
292 Local Variables:
293 mode:c++
294 c-file-style:"stroustrup"
295 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
296 indent-tabs-mode:nil
297 fill-column:99
298 End:
299 */
300 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :
301 #endif