/data/refman/pasoursint/CMSSW_5_3_0/src/DataFormats/Math/src/FastMath.cc

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#include "DataFormats/Math/interface/FastMath.h"
namespace fastmath_details {
  float atanbuf_[257 * 2];
  double datanbuf_[513 * 2];

  namespace {
    // ====================================================================
    // arctan initialization
    // =====================================================================
    struct Initatan {
      Initatan() {
        unsigned int ind;
        for (ind = 0; ind <= 256; ind++) {
          double v = ind / 256.0;
          double asinv = ::asin(v);
          atanbuf_[ind * 2    ] = ::cos(asinv);
          atanbuf_[ind * 2 + 1] = asinv;
        }
        for (ind = 0; ind <= 512; ind++) {
          double v = ind / 512.0;
          double asinv = ::asin(v);
          datanbuf_[ind * 2    ] = ::cos(asinv);
          datanbuf_[ind * 2 + 1] = asinv;
        }
      }
    };
    static Initatan initAtan;
  }
}