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"
42 #include "utils.h"
44 namespace Geom {
46 /*** An empty SBasis is identically 0. */
47 class SBasis : public std::vector<Linear>{
48 public:
49 SBasis() {}
50 explicit SBasis(double a) {
51 push_back(Linear(a,a));
52 }
53 SBasis(SBasis const & a) :
54 std::vector<Linear>(a)
55 {}
56 SBasis(Linear const & bo) {
57 push_back(bo);
58 }
60 //IMPL: FragmentConcept
61 typedef double output_type;
62 inline bool isZero() const {
63 if(empty()) return true;
64 for(unsigned i = 0; i < size(); i++) {
65 if(!(*this)[i].isZero()) return false;
66 }
67 return true;
68 }
69 bool isFinite() const;
70 inline double at0() const {
71 if(empty()) return 0; else return (*this)[0][0];
72 }
73 inline double at1() const{
74 if(empty()) return 0; else return (*this)[0][1];
75 }
77 double valueAt(double t) const {
78 double s = t*(1-t);
79 double p0 = 0, p1 = 0;
80 double sk = 1;
81 //TODO: rewrite as horner
82 for(unsigned k = 0; k < size(); k++) {
83 p0 += sk*(*this)[k][0];
84 p1 += sk*(*this)[k][1];
85 sk *= s;
86 }
87 return (1-t)*p0 + t*p1;
88 }
89 double valueAndDerivative(double t, double &der) const {
90 double s = t*(1-t);
91 double p0 = 0, p1 = 0;
92 double sk = 1;
93 //TODO: rewrite as horner
94 for(unsigned k = 0; k < size(); k++) {
95 p0 += sk*(*this)[k][0];
96 p1 += sk*(*this)[k][1];
97 sk *= s;
98 }
99 // p0 and p1 at this point form a linear approximation at t
100 der = p1 - p0;
101 return (1-t)*p0 + t*p1;
102 }
103 double operator()(double t) const {
104 return valueAt(t);
105 }
107 std::vector<double> valueAndDerivatives(double /*t*/, unsigned /*n*/) const {
108 //TODO
109 throw NotImplemented();
110 }
112 SBasis toSBasis() const { return SBasis(*this); }
114 double tailError(unsigned tail) const;
116 // compute f(g)
117 SBasis operator()(SBasis const & g) const;
119 Linear operator[](unsigned i) const {
120 assert(i < size());
121 return std::vector<Linear>::operator[](i);
122 }
124 //MUTATOR PRISON
125 Linear& operator[](unsigned i) { return this->at(i); }
127 //remove extra zeros
128 void normalize() {
129 while(!empty() && 0 == back()[0] && 0 == back()[1])
130 pop_back();
131 }
132 void truncate(unsigned k) { if(k < size()) resize(k); }
133 };
135 //TODO: figure out how to stick this in linear, while not adding an sbasis dep
136 inline SBasis Linear::toSBasis() const { return SBasis(*this); }
138 //implemented in sbasis-roots.cpp
139 Interval bounds_exact(SBasis const &a);
140 Interval bounds_fast(SBasis const &a, int order = 0);
141 Interval bounds_local(SBasis const &a, const Interval &t, int order = 0);
143 inline SBasis reverse(SBasis const &a) {
144 SBasis result;
145 result.reserve(a.size());
146 for(unsigned k = 0; k < a.size(); k++)
147 result.push_back(reverse(a[k]));
148 return result;
149 }
151 //IMPL: ScalableConcept
152 inline SBasis operator-(const SBasis& p) {
153 if(p.isZero()) return SBasis();
154 SBasis result;
155 result.reserve(p.size());
157 for(unsigned i = 0; i < p.size(); i++) {
158 result.push_back(-p[i]);
159 }
160 return result;
161 }
162 SBasis operator*(SBasis const &a, double k);
163 inline SBasis operator*(double k, SBasis const &a) { return a*k; }
164 inline SBasis operator/(SBasis const &a, double k) { return a*(1./k); }
165 SBasis& operator*=(SBasis& a, double b);
166 inline SBasis& operator/=(SBasis& a, double b) { return (a*=(1./b)); }
168 //IMPL: AddableConcept
169 SBasis operator+(const SBasis& a, const SBasis& b);
170 SBasis operator-(const SBasis& a, const SBasis& b);
171 SBasis& operator+=(SBasis& a, const SBasis& b);
172 SBasis& operator-=(SBasis& a, const SBasis& b);
174 //TODO: remove?
175 inline SBasis operator+(const SBasis & a, Linear const & b) {
176 if(b.isZero()) return a;
177 if(a.isZero()) return b;
178 SBasis result(a);
179 result[0] += b;
180 return result;
181 }
182 inline SBasis operator-(const SBasis & a, Linear const & b) {
183 if(b.isZero()) return a;
184 SBasis result(a);
185 result[0] -= b;
186 return result;
187 }
188 inline SBasis& operator+=(SBasis& a, const Linear& b) {
189 if(a.isZero())
190 a.push_back(b);
191 else
192 a[0] += b;
193 return a;
194 }
195 inline SBasis& operator-=(SBasis& a, const Linear& b) {
196 if(a.isZero())
197 a.push_back(-b);
198 else
199 a[0] -= b;
200 return a;
201 }
203 //IMPL: OffsetableConcept
204 inline SBasis operator+(const SBasis & a, double b) {
205 if(a.isZero()) return Linear(b, b);
206 SBasis result(a);
207 result[0] += b;
208 return result;
209 }
210 inline SBasis operator-(const SBasis & a, double b) {
211 if(a.isZero()) return Linear(-b, -b);
212 SBasis result(a);
213 result[0] -= b;
214 return result;
215 }
216 inline SBasis& operator+=(SBasis& a, double b) {
217 if(a.isZero())
218 a.push_back(Linear(b,b));
219 else
220 a[0] += b;
221 return a;
222 }
223 inline SBasis& operator-=(SBasis& a, double b) {
224 if(a.isZero())
225 a.push_back(Linear(-b,-b));
226 else
227 a[0] -= b;
228 return a;
229 }
231 SBasis shift(SBasis const &a, int sh);
232 SBasis shift(Linear const &a, int sh);
234 inline SBasis truncate(SBasis const &a, unsigned terms) {
235 SBasis c;
236 c.insert(c.begin(), a.begin(), a.begin() + std::min(terms, (unsigned)a.size()));
237 return c;
238 }
240 SBasis multiply(SBasis const &a, SBasis const &b);
242 SBasis integral(SBasis const &c);
243 SBasis derivative(SBasis const &a);
245 SBasis sqrt(SBasis const &a, int k);
247 // return a kth order approx to 1/a)
248 SBasis reciprocal(Linear const &a, int k);
249 SBasis divide(SBasis const &a, SBasis const &b, int k);
251 inline SBasis operator*(SBasis const & a, SBasis const & b) {
252 return multiply(a, b);
253 }
255 inline SBasis& operator*=(SBasis& a, SBasis const & b) {
256 a = multiply(a, b);
257 return a;
258 }
260 //valuation: degree of the first non zero coefficient.
261 inline unsigned
262 valuation(SBasis const &a, double tol=0){
263 unsigned val=0;
264 while( val<a.size() &&
265 fabs(a[val][0])<tol &&
266 fabs(a[val][1])<tol )
267 val++;
268 return val;
269 }
271 // a(b(t))
272 SBasis compose(SBasis const &a, SBasis const &b);
273 SBasis compose(SBasis const &a, SBasis const &b, unsigned k);
274 SBasis inverse(SBasis a, int k);
275 //compose_inverse(f,g)=compose(f,inverse(g)), but is numerically more stable in some good cases...
276 //TODO: requires g(0)=0 & g(1)=1 atm. generalization should be obvious.
277 SBasis compose_inverse(SBasis const &f, SBasis const &g, unsigned order=2, double tol=1e-3);
279 inline SBasis portion(const SBasis &t, double from, double to) { return compose(t, Linear(from, to)); }
281 // compute f(g)
282 inline SBasis
283 SBasis::operator()(SBasis const & g) const {
284 return compose(*this, g);
285 }
287 inline std::ostream &operator<< (std::ostream &out_file, const Linear &bo) {
288 out_file << "{" << bo[0] << ", " << bo[1] << "}";
289 return out_file;
290 }
292 inline std::ostream &operator<< (std::ostream &out_file, const SBasis & p) {
293 for(unsigned i = 0; i < p.size(); i++) {
294 out_file << p[i] << "s^" << i << " + ";
295 }
296 return out_file;
297 }
299 SBasis sin(Linear bo, int k);
300 SBasis cos(Linear bo, int k);
302 std::vector<double> roots(SBasis const & s);
303 std::vector<std::vector<double> > multi_roots(SBasis const &f,
304 std::vector<double> const &levels,
305 double htol=1e-7,
306 double vtol=1e-7,
307 double a=0,
308 double b=1);
310 }
312 /*
313 Local Variables:
314 mode:c++
315 c-file-style:"stroustrup"
316 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
317 indent-tabs-mode:nil
318 fill-column:99
319 End:
320 */
321 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :
322 #endif