1 /////////////////////////////////////////////////////////////////
4 // Routines for doing math operations in PROBCONS.
5 /////////////////////////////////////////////////////////////////
15 typedef float ScoreType;
17 const float LOG_ZERO = -2e20;
18 const float LOG_ONE = 0.0;
20 /////////////////////////////////////////////////////////////////
23 // Compute the logarithm of x.
24 /////////////////////////////////////////////////////////////////
26 inline ScoreType LOG (ScoreType x){
30 /////////////////////////////////////////////////////////////////
34 /////////////////////////////////////////////////////////////////
36 inline ScoreType EXP (ScoreType x){
42 return (((0.03254409303190190000*x + 0.16280432765779600000)*x + 0.49929760485974900000)*x + 0.99995149601363700000)*x + 0.99999925508501600000;
45 return (((0.01973899026052090000*x + 0.13822379685007000000)*x + 0.48056651562365000000)*x + 0.99326940370383500000)*x + 0.99906756856399500000;
46 return (((0.00940528203591384000*x + 0.09414963667859410000)*x + 0.40825793595877300000)*x + 0.93933625499130400000)*x + 0.98369508190545300000;
50 return (((0.00217245711583303000*x + 0.03484829428350620000)*x + 0.22118199801337800000)*x + 0.67049462206469500000)*x + 0.83556950223398500000;
51 return (((0.00012398771025456900*x + 0.00349155785951272000)*x + 0.03727721426017900000)*x + 0.17974997741536900000)*x + 0.33249299994217400000;
54 return (((0.00000051741713416603*x + 0.00002721456879608080)*x + 0.00053418601865636800)*x + 0.00464101989351936000)*x + 0.01507447981459420000;
59 /////////////////////////////////////////////////////////////////
62 // Computes log (exp (x) + 1), for 0 <= x <= 7.5.
63 /////////////////////////////////////////////////////////////////
65 inline ScoreType LOOKUP (ScoreType x){
66 //return log (exp(x) + 1);
70 return log (exp(x) + 1);
71 return (((-0.00486373205785640000*x - 0.00020245408813934800)*x + 0.12504222666029800000)*x + 0.49999685320563000000)*x + 0.69314723138948900000;
74 return (((-0.00278634205460548000*x - 0.00458097251248546000)*x + 0.12865849880472500000)*x + 0.49862228499205200000)*x + 0.69334810088688000000;
75 return (((0.00059633755154209200*x - 0.01918996666063320000)*x + 0.15288232492093800000)*x + 0.48039958825756900000)*x + 0.69857578503189200000;
79 return (((0.00135958539181047000*x - 0.02329807659316430000)*x + 0.15885799609532100000)*x + 0.48167498563270800000)*x + 0.69276185058669200000;
80 return (((0.00011992394456683500*x - 0.00338464503306568000)*x + 0.03622746366545470000)*x + 0.82481250248383700000)*x + 0.32507892994863100000;
83 return (((0.00000051726300753785*x - 0.00002720671238876090)*x + 0.00053403733818413500)*x + 0.99536021775747900000)*x + 0.01507065715532010000;
87 /////////////////////////////////////////////////////////////////
90 // Computes log (exp (x) + 1).
91 /////////////////////////////////////////////////////////////////
93 inline ScoreType LOOKUP_SLOW (ScoreType x){
94 return log (exp (x) + 1);
97 /////////////////////////////////////////////////////////////////
100 // Compute max of three numbers
101 /////////////////////////////////////////////////////////////////
103 inline ScoreType MAX (ScoreType x, ScoreType y, ScoreType z){
114 /////////////////////////////////////////////////////////////////
117 // Add two log probabilities and store in the first argument
118 /////////////////////////////////////////////////////////////////
120 inline void LOG_PLUS_EQUALS (ScoreType &x, ScoreType y){
122 x = (x <= LOG_ZERO) ? y : LOOKUP(y-x) + x;
124 x = (y <= LOG_ZERO) ? x : LOOKUP(x-y) + y;
127 /////////////////////////////////////////////////////////////////
128 // LOG_PLUS_EQUALS_SLOW()
130 // Add two log probabilities and store in the first argument
131 /////////////////////////////////////////////////////////////////
133 inline void LOG_PLUS_EQUALS_SLOW (ScoreType &x, ScoreType y){
135 x = (x <= LOG_ZERO) ? y : LOOKUP_SLOW(y-x) + x;
137 x = (y <= LOG_ZERO) ? x : LOOKUP_SLOW(x-y) + y;
140 /////////////////////////////////////////////////////////////////
143 // Add two log probabilities
144 /////////////////////////////////////////////////////////////////
146 inline ScoreType LOG_ADD (ScoreType x, ScoreType y){
147 if (x < y) return (x <= LOG_ZERO) ? y : LOOKUP(y-x) + x;
148 return (y <= LOG_ZERO) ? x : LOOKUP(x-y) + y;
153 /////////////////////////////////////////////////////////////////
156 // Compute the logarithm of x.
157 /////////////////////////////////////////////////////////////////
159 inline float LOG (float x){
163 /////////////////////////////////////////////////////////////////
166 // Computes exp(x), fr -4.6 <= x <= 0.
167 /////////////////////////////////////////////////////////////////
169 inline float EXP (float x){
171 if (x < EXP_UNDERFLOW_THRESHOLD) return 0.0f;
172 return (((0.006349841068584 * x + 0.080775412572352) * x + 0.397982026296272) * x + 0.95279335963787f) * x + 0.995176455837312f;
173 //return (((0.00681169825657f * x + 0.08386267698832f) * x + 0.40413983195844f) * x + 0.95656674979767f) * x + 0.99556744049130f;
177 const float EXP_UNDERFLOW_THRESHOLD = -4.6;
178 const float LOG_UNDERFLOW_THRESHOLD = 7.5;
180 /////////////////////////////////////////////////////////////////
183 // Computes log (exp (x) + 1), for 0 <= x <= 7.5.
184 /////////////////////////////////////////////////////////////////
186 inline float LOOKUP (float x){
188 assert (x <= LOG_UNDERFLOW_THRESHOLD);
189 //return ((-0.00653779113685f * x + 0.09537236626558f) * x + 0.55317574459331f) * x + 0.68672959851568f;
190 if (x <= 1.00f) return ((-0.009350833524763f * x + 0.130659527668286f) * x + 0.498799810682272f) * x + 0.693203116424741f;
191 if (x <= 2.50f) return ((-0.014532321752540f * x + 0.139942324101744f) * x + 0.495635523139337f) * x + 0.692140569840976f;
192 if (x <= 4.50f) return ((-0.004605031767994f * x + 0.063427417320019f) * x + 0.695956496475118f) * x + 0.514272634594009f;
193 assert (x <= LOG_UNDERFLOW_THRESHOLD);
194 return ((-0.000458661602210f * x + 0.009695946122598f) * x + 0.930734667215156f) * x + 0.168037164329057f;
196 //return (((0.00089738532761f * x - 0.01859488697982f) * x + 0.14415772028626f) * x + 0.49515490689159f) * x + 0.69311928966454f;
199 /////////////////////////////////////////////////////////////////
202 // Computes log (exp (x) + 1).
203 /////////////////////////////////////////////////////////////////
205 inline float LOOKUP_SLOW (float x){
206 return log (exp (x) + 1);
209 /////////////////////////////////////////////////////////////////
212 // Compute max of three numbers
213 /////////////////////////////////////////////////////////////////
215 inline float MAX (float x, float y, float z){
226 /////////////////////////////////////////////////////////////////
229 // Add two log probabilities and store in the first argument
230 /////////////////////////////////////////////////////////////////
232 inline void LOG_PLUS_EQUALS (float &x, float y){
234 x = (x == LOG_ZERO || y - x >= LOG_UNDERFLOW_THRESHOLD) ? y : LOOKUP(y-x) + x;
236 x = (y == LOG_ZERO || x - y >= LOG_UNDERFLOW_THRESHOLD) ? x : LOOKUP(x-y) + y;
239 /////////////////////////////////////////////////////////////////
240 // LOG_PLUS_EQUALS_SLOW()
242 // Add two log probabilities and store in the first argument
243 /////////////////////////////////////////////////////////////////
245 inline void LOG_PLUS_EQUALS_SLOW (float &x, float y){
247 x = (x == LOG_ZERO) ? y : LOOKUP_SLOW(y-x) + x;
249 x = (y == LOG_ZERO) ? x : LOOKUP_SLOW(x-y) + y;
252 /////////////////////////////////////////////////////////////////
255 // Add two log probabilities
256 /////////////////////////////////////////////////////////////////
258 inline float LOG_ADD (float x, float y){
259 if (x < y) return (x == LOG_ZERO || y - x >= LOG_UNDERFLOW_THRESHOLD) ? y : LOOKUP(y-x) + x;
260 return (y == LOG_ZERO || x - y >= LOG_UNDERFLOW_THRESHOLD) ? x : LOOKUP(x-y) + y;
264 /////////////////////////////////////////////////////////////////
267 // Add three log probabilities
268 /////////////////////////////////////////////////////////////////
270 inline float LOG_ADD (float x1, float x2, float x3){
271 return LOG_ADD (x1, LOG_ADD (x2, x3));
274 /////////////////////////////////////////////////////////////////
277 // Add four log probabilities
278 /////////////////////////////////////////////////////////////////
280 inline float LOG_ADD (float x1, float x2, float x3, float x4){
281 return LOG_ADD (x1, LOG_ADD (x2, LOG_ADD (x3, x4)));
284 /////////////////////////////////////////////////////////////////
287 // Add five log probabilities
288 /////////////////////////////////////////////////////////////////
290 inline float LOG_ADD (float x1, float x2, float x3, float x4, float x5){
291 return LOG_ADD (x1, LOG_ADD (x2, LOG_ADD (x3, LOG_ADD (x4, x5))));
294 /////////////////////////////////////////////////////////////////
297 // Add siz log probabilities
298 /////////////////////////////////////////////////////////////////
300 inline float LOG_ADD (float x1, float x2, float x3, float x4, float x5, float x6){
301 return LOG_ADD (x1, LOG_ADD (x2, LOG_ADD (x3, LOG_ADD (x4, LOG_ADD (x5, x6)))));
304 /////////////////////////////////////////////////////////////////
307 // Add seven log probabilities
308 /////////////////////////////////////////////////////////////////
310 inline float LOG_ADD (float x1, float x2, float x3, float x4, float x5, float x6, float x7){
311 return LOG_ADD (x1, LOG_ADD (x2, LOG_ADD (x3, LOG_ADD (x4, LOG_ADD (x5, LOG_ADD (x6, x7))))));
314 /////////////////////////////////////////////////////////////////
315 // ChooseBestOfThree()
317 // Store the largest of three values x1, x2, and x3 in *x. Also
318 // if xi is the largest value, then store bi in *b.
319 /////////////////////////////////////////////////////////////////
321 inline void ChooseBestOfThree (float x1, float x2, float x3, char b1, char b2, char b3, float *x, char *b){