ENH:remove otbGamma.h (use boost function instead)

Code/Common/otbGamma.h

-/*=========================================================================
-
-  Program:   ORFEO Toolbox
-  Language:  C++
-  Date:      $Date$
-  Version:   $Revision$
-
-
-  Copyright (c) Centre National d'Etudes Spatiales. All rights reserved.
-  See OTBCopyright.txt for details.
-
-  This code is from a Jan Wegner contribution.
-
-
-     This software is distributed WITHOUT ANY WARRANTY; without even
-     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
-     PURPOSE.  See the above copyright notices for more information.
-
-=========================================================================*/
-#ifndef __otbGamma_h
-#define __otbGamma_h
-
-#include "otbMath.h"
-
-namespace otb
-{
-/** \class Gamma
- *  \brief Gamma function
- *
- */
-class Gamma {
-public:
-  double gamma(double x)
-  {
-    int m;
-    double ga, gr, r, z;
-
-    static double g[] = {
-      1.0,
-      0.5772156649015329,
-      -0.6558780715202538,
-      -0.420026350340952e-1,
-      0.1665386113822915,
-      -0.421977345555443e-1,
-      -0.9621971527877e-2,
-      0.7218943246663e-2,
-      -0.11651675918591e-2,
-      -0.2152416741149e-3,
-      0.1280502823882e-3,
-      -0.201348547807e-4,
-      -0.12504934821e-5,
-      0.1133027232e-5,
-      -0.2056338417e-6,
-      0.6116095e-8,
-      0.50020075e-8,
-      -0.11812746e-8,
-      0.1043427e-9,
-      0.77823e-11,
-      -0.36968e-11,
-      0.51e-12,
-      -0.206e-13,
-      -0.54e-14,
-      0.14e-14};
-
-    if (x > 171.0) return 1e308;    // This value is an overflow flag.
-    if (x == (int)x)
-      {
-      if (x > 0.0)
-        {
-        ga = 1.0;               // use factorial
-        for (int i = 2; i < x; ++i)
-          {
-          ga *= i;
-          }
-        }
-      else ga = 1e308;
-      }
-    else
-      {
-      if (vcl_abs(x) > 1.0)
-        {
-        z = vcl_abs(x);
-        m = (int)z;
-        r = 1.0;
-        for (int k = 1; k <= m; ++k)
-          {
-          r *= (z-k);
-          }
-        z -= m;
-        }
-      else z = x;
-      gr = g[24];
-      for (int k = 23; k >= 0; k--)
-        {
-        gr = gr*z+g[k];
-        }
-      ga = 1.0/(gr*z);
-      if (vcl_abs(x) > 1.0)
-        {
-        ga *= r;
-        if (x < 0.0)
-          {
-          ga = -otb::CONST_PI/(x*ga*vcl_sin(otb::CONST_PI*x));
-          }
-        }
-      }
-    return ga;
-  }
-};
-} // end namespace otb
-
-#endif