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RandomNumbers.cpp
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00034 
00035 /* Author: Ioan Sucan */
00036 
00037 #include "ompl/util/RandomNumbers.h"
00038 #include "ompl/util/Exception.h"
00039 #include "ompl/util/Console.h"
00040 #include <boost/random/lagged_fibonacci.hpp>
00041 #include <boost/random/uniform_int.hpp>
00042 #include <boost/thread/mutex.hpp>
00043 #include <boost/date_time/posix_time/posix_time.hpp>
00044 #include <boost/math/constants/constants.hpp>
00045 
00047 static boost::uint32_t userSetSeed = 0;
00048 
00050 static bool            firstSeedGenerated = false;
00051 
00053 static boost::uint32_t firstSeedValue = 0;
00054 
00056 static boost::uint32_t firstSeed(void)
00057 {
00058     static boost::mutex fsLock;
00059     boost::mutex::scoped_lock slock(fsLock);
00060 
00061     if (firstSeedGenerated)
00062         return firstSeedValue;
00063 
00064     if (userSetSeed != 0)
00065         firstSeedValue = userSetSeed;
00066     else
00067         firstSeedValue =
00068             (boost::uint32_t)(boost::posix_time::microsec_clock::universal_time() -
00069                               boost::posix_time::ptime(boost::date_time::min_date_time)).total_microseconds();
00070     firstSeedGenerated = true;
00071 
00072     return firstSeedValue;
00073 }
00074 
00078 static boost::uint32_t nextSeed(void)
00079 {
00080     static boost::mutex rngMutex;
00081     rngMutex.lock();
00082     static boost::lagged_fibonacci607 sGen(firstSeed());
00083     static boost::uniform_int<>       sDist(1, 1000000000);
00084     static boost::variate_generator<boost::lagged_fibonacci607&, boost::uniform_int<> > s(sGen, sDist);
00085     boost::uint32_t v = s();
00086     rngMutex.unlock();
00087     return v;
00088 }
00089 
00090 boost::uint32_t ompl::RNG::getSeed(void)
00091 {
00092     return firstSeed();
00093 }
00094 
00095 void ompl::RNG::setSeed(boost::uint32_t seed)
00096 {
00097     if (firstSeedGenerated)
00098     {
00099         msg::Interface msg;
00100         msg.error("Random number generation already started. Changing seed now will not lead to deterministic sampling.");
00101     }
00102     if (seed == 0)
00103     {
00104         msg::Interface msg;
00105         msg.warn("Random generator seed cannot be 0. Using 1 instead.");
00106         userSetSeed = 1;
00107     }
00108     else
00109         userSetSeed = seed;
00110 }
00111 
00112 ompl::RNG::RNG(void) : generator_(nextSeed()),
00113                        uniDist_(0, 1),
00114                        normalDist_(0, 1),
00115                        uni_(generator_, uniDist_),
00116                        normal_(generator_, normalDist_)
00117 {
00118 }
00119 
00120 double ompl::RNG::halfNormalReal(double r_min, double r_max, double focus)
00121 {
00122     assert(r_min <= r_max);
00123 
00124     const double mean = r_max - r_min;
00125     double       v    = gaussian(mean, mean/focus);
00126 
00127     if (v > mean) v = 2.0 * mean - v;
00128     double r = v >= 0.0 ? v + r_min : r_min;
00129     return r > r_max ? r_max : r;
00130 }
00131 
00132 int ompl::RNG::halfNormalInt(int r_min, int r_max, double focus)
00133 {
00134     int r = (int)floor(halfNormalReal((double)r_min, (double)(r_max) + 1.0, focus));
00135     return (r > r_max) ? r_max : r;
00136 }
00137 
00138 // From: "Uniform Random Rotations", Ken Shoemake, Graphics Gems III,
00139 //       pg. 124-132
00140 void ompl::RNG::quaternion(double value[4])
00141 {
00142     double x0 = uni_();
00143     double r1 = sqrt(1.0 - x0), r2 = sqrt(x0);
00144     double t1 = 2.0 * boost::math::constants::pi<double>() * uni_(), t2 = 2.0 * boost::math::constants::pi<double>() * uni_();
00145     double c1 = cos(t1), s1 = sin(t1);
00146     double c2 = cos(t2), s2 = sin(t2);
00147     value[0] = s1 * r1;
00148     value[1] = c1 * r1;
00149     value[2] = s2 * r2;
00150     value[3] = c2 * r2;
00151 }