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"
43 #include "exception.h"
45 namespace Geom {
47 /*** An empty SBasis is identically 0. */
48 class SBasis : public std::vector<Linear>{
49 public:
50 SBasis() {}
51 explicit SBasis(double a) {
52 push_back(Linear(a,a));
53 }
54 SBasis(SBasis const & a) :
55 std::vector<Linear>(a)
56 {}
57 SBasis(Linear const & bo) {
58 push_back(bo);
59 }
61 //IMPL: FragmentConcept
62 typedef double output_type;
63 inline bool isZero() const {
64 if(empty()) return true;
65 for(unsigned i = 0; i < size(); i++) {
66 if(!(*this)[i].isZero()) return false;
67 }
68 return true;
69 }
70 inline bool isConstant() const {
71 if (empty()) return true;
72 for (unsigned i = 0; i < size(); i++) {
73 if(!(*this)[i].isConstant()) return false;
74 }
75 return true;
76 }
78 bool isFinite() const;
79 inline double at0() const {
80 if(empty()) return 0; else return (*this)[0][0];
81 }
82 inline double at1() const{
83 if(empty()) return 0; else return (*this)[0][1];
84 }
86 double valueAt(double t) const {
87 double s = t*(1-t);
88 double p0 = 0, p1 = 0;
89 double sk = 1;
90 //TODO: rewrite as horner
91 for(unsigned k = 0; k < size(); k++) {
92 p0 += sk*(*this)[k][0];
93 p1 += sk*(*this)[k][1];
94 sk *= s;
95 }
96 return (1-t)*p0 + t*p1;
97 }
98 double valueAndDerivative(double t, double &der) const {
99 double s = t*(1-t);
100 double p0 = 0, p1 = 0;
101 double sk = 1;
102 //TODO: rewrite as horner
103 for(unsigned k = 0; k < size(); k++) {
104 p0 += sk*(*this)[k][0];
105 p1 += sk*(*this)[k][1];
106 sk *= s;
107 }
108 // p0 and p1 at this point form a linear approximation at t
109 der = p1 - p0;
110 return (1-t)*p0 + t*p1;
111 }
112 double operator()(double t) const {
113 return valueAt(t);
114 }
116 std::vector<double> valueAndDerivatives(double t, unsigned n) const;
118 SBasis toSBasis() const { return SBasis(*this); }
120 double tailError(unsigned tail) const;
122 // compute f(g)
123 SBasis operator()(SBasis const & g) const;
125 Linear operator[](unsigned i) const {
126 assert(i < size());
127 return std::vector<Linear>::operator[](i);
128 }
130 //MUTATOR PRISON
131 Linear& operator[](unsigned i) { return this->at(i); }
133 //remove extra zeros
134 void normalize() {
135 while(!empty() && 0 == back()[0] && 0 == back()[1])
136 pop_back();
137 }
138 void truncate(unsigned k) { if(k < size()) resize(k); }
139 };
141 //TODO: figure out how to stick this in linear, while not adding an sbasis dep
142 inline SBasis Linear::toSBasis() const { return SBasis(*this); }
144 //implemented in sbasis-roots.cpp
145 Interval bounds_exact(SBasis const &a);
146 Interval bounds_fast(SBasis const &a, int order = 0);
147 Interval bounds_local(SBasis const &a, const Interval &t, int order = 0);
149 inline SBasis reverse(SBasis const &a) {
150 SBasis result;
151 result.reserve(a.size());
152 for(unsigned k = 0; k < a.size(); k++)
153 result.push_back(reverse(a[k]));
154 return result;
155 }
157 //IMPL: ScalableConcept
158 inline SBasis operator-(const SBasis& p) {
159 if(p.isZero()) return SBasis();
160 SBasis result;
161 result.reserve(p.size());
163 for(unsigned i = 0; i < p.size(); i++) {
164 result.push_back(-p[i]);
165 }
166 return result;
167 }
168 SBasis operator*(SBasis const &a, double k);
169 inline SBasis operator*(double k, SBasis const &a) { return a*k; }
170 inline SBasis operator/(SBasis const &a, double k) { return a*(1./k); }
171 SBasis& operator*=(SBasis& a, double b);
172 inline SBasis& operator/=(SBasis& a, double b) { return (a*=(1./b)); }
174 //IMPL: AddableConcept
175 SBasis operator+(const SBasis& a, const SBasis& b);
176 SBasis operator-(const SBasis& a, const SBasis& b);
177 SBasis& operator+=(SBasis& a, const SBasis& b);
178 SBasis& operator-=(SBasis& a, const SBasis& b);
180 //TODO: remove?
181 inline SBasis operator+(const SBasis & a, Linear const & b) {
182 if(b.isZero()) return a;
183 if(a.isZero()) return b;
184 SBasis result(a);
185 result[0] += b;
186 return result;
187 }
188 inline SBasis operator-(const SBasis & a, Linear const & b) {
189 if(b.isZero()) return a;
190 SBasis result(a);
191 result[0] -= b;
192 return result;
193 }
194 inline SBasis& operator+=(SBasis& a, const Linear& b) {
195 if(a.isZero())
196 a.push_back(b);
197 else
198 a[0] += b;
199 return a;
200 }
201 inline SBasis& operator-=(SBasis& a, const Linear& b) {
202 if(a.isZero())
203 a.push_back(-b);
204 else
205 a[0] -= b;
206 return a;
207 }
209 //IMPL: OffsetableConcept
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-(const SBasis & a, double b) {
217 if(a.isZero()) return Linear(-b, -b);
218 SBasis result(a);
219 result[0] -= b;
220 return result;
221 }
222 inline SBasis& operator+=(SBasis& a, double b) {
223 if(a.isZero())
224 a.push_back(Linear(b,b));
225 else
226 a[0] += b;
227 return a;
228 }
229 inline SBasis& operator-=(SBasis& a, double b) {
230 if(a.isZero())
231 a.push_back(Linear(-b,-b));
232 else
233 a[0] -= b;
234 return a;
235 }
237 SBasis shift(SBasis const &a, int sh);
238 SBasis shift(Linear const &a, int sh);
240 inline SBasis truncate(SBasis const &a, unsigned terms) {
241 SBasis c;
242 c.insert(c.begin(), a.begin(), a.begin() + std::min(terms, (unsigned)a.size()));
243 return c;
244 }
246 SBasis multiply(SBasis const &a, SBasis const &b);
248 SBasis integral(SBasis const &c);
249 SBasis derivative(SBasis const &a);
251 SBasis sqrt(SBasis const &a, int k);
253 // return a kth order approx to 1/a)
254 SBasis reciprocal(Linear const &a, int k);
255 SBasis divide(SBasis const &a, SBasis const &b, int k);
257 inline SBasis operator*(SBasis const & a, SBasis const & b) {
258 return multiply(a, b);
259 }
261 inline SBasis& operator*=(SBasis& a, SBasis const & b) {
262 a = multiply(a, b);
263 return a;
264 }
266 //valuation: degree of the first non zero coefficient.
267 inline unsigned
268 valuation(SBasis const &a, double tol=0){
269 unsigned val=0;
270 while( val<a.size() &&
271 fabs(a[val][0])<tol &&
272 fabs(a[val][1])<tol )
273 val++;
274 return val;
275 }
277 // a(b(t))
278 SBasis compose(SBasis const &a, SBasis const &b);
279 SBasis compose(SBasis const &a, SBasis const &b, unsigned k);
280 SBasis inverse(SBasis a, int k);
281 //compose_inverse(f,g)=compose(f,inverse(g)), but is numerically more stable in some good cases...
282 //TODO: requires g(0)=0 & g(1)=1 atm. generalization should be obvious.
283 SBasis compose_inverse(SBasis const &f, SBasis const &g, unsigned order=2, double tol=1e-3);
285 inline SBasis portion(const SBasis &t, double from, double to) { return compose(t, Linear(from, to)); }
287 // compute f(g)
288 inline SBasis
289 SBasis::operator()(SBasis const & g) const {
290 return compose(*this, g);
291 }
293 inline std::ostream &operator<< (std::ostream &out_file, const Linear &bo) {
294 out_file << "{" << bo[0] << ", " << bo[1] << "}";
295 return out_file;
296 }
298 inline std::ostream &operator<< (std::ostream &out_file, const SBasis & p) {
299 for(unsigned i = 0; i < p.size(); i++) {
300 out_file << p[i] << "s^" << i << " + ";
301 }
302 return out_file;
303 }
305 SBasis sin(Linear bo, int k);
306 SBasis cos(Linear bo, int k);
308 std::vector<double> roots(SBasis const & s);
309 std::vector<std::vector<double> > multi_roots(SBasis const &f,
310 std::vector<double> const &levels,
311 double htol=1e-7,
312 double vtol=1e-7,
313 double a=0,
314 double b=1);
316 }
318 /*
319 Local Variables:
320 mode:c++
321 c-file-style:"stroustrup"
322 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
323 indent-tabs-mode:nil
324 fill-column:99
325 End:
326 */
327 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :
328 #endif