dither.cpp
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00034 
00035 // Original version: Kevin Watts <watts@willowgarage.com>
00036 
00037 #include <control_toolbox/dither.h>
00038 
00039 namespace control_toolbox {
00040 
00041 Dither::Dither() : amplitude_(0), has_saved_value_(false)
00042 {
00043 
00044 }
00045 
00046 Dither::~Dither()
00047 {
00048 }
00049 
00050 double Dither::update()
00051 {
00052   if (has_saved_value_)
00053   {
00054     has_saved_value_ = false;
00055     return saved_value_;
00056   }
00057 
00058   // Generates gaussian random noise using the polar method.
00059   double v1, v2, r;
00060   for (int i = 0; i < 100; ++i)
00061   {
00062     v1 = 2.0 * erand48(seed_) - 1.0;  //  [-1, 1]
00063     v2 = 2.0 * erand48(seed_) - 1.0;  //  [-1, 1]
00064     r = v1*v1 + v2*v2;
00065     if (r <= 1.0)
00066       break;
00067   }
00068   if (r > 1.0)
00069     r = 1.0;
00070 
00071   double f = sqrt(-2.0 * log(r) / r);
00072   double current = amplitude_ * f * v1;
00073   saved_value_ = amplitude_ * f * v2;
00074   has_saved_value_ = true;
00075 
00076   return current;
00077 }
00078 
00079 }


control_toolbox
Author(s): Melonee Wise, Sachin Chitta, John Hsu
autogenerated on Fri Jan 3 2014 11:41:22