betainc.cc

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/*

Copyright (C) 1997-2012 John W. Eaton

This file is part of Octave.

Octave is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3 of the License, or (at your
option) any later version.

Octave is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with Octave; see the file COPYING.  If not, see
<http://www.gnu.org/licenses/>.

*/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "lo-specfun.h"

#include "defun-dld.h"
#include "error.h"
#include "gripes.h"
#include "oct-obj.h"
#include "utils.h"

DEFUN_DLD (betainc, args, ,
  "-*- texinfo -*-\n\
@deftypefn {Mapping Function} {} betainc (@var{x}, @var{a}, @var{b})\n\
Return the regularized incomplete Beta function,\n\
@tex\n\
$$\n\
 I (x, a, b) = {1 \\over {B (a, b)}} \\int_0^x t^{(a-z)} (1-t)^{(b-1)} dt.\n\
$$\n\
@end tex\n\
@ifnottex\n\
@c Set example in small font to prevent overfull line\n\
\n\
@smallexample\n\
@group\n\
@c spacing appears odd here, but is correct after Makeinfo\n\
                                     x\n\
                          1         /\n\
betainc (x, a, b) = -----------    | t^(a-1) (1-t)^(b-1) dt.\n\
                     beta (a, b)    /\n\
                                 t=0\n\
@end group\n\
@end smallexample\n\
\n\
@end ifnottex\n\
\n\
If @var{x} has more than one component, both @var{a} and @var{b} must be\n\
scalars.  If @var{x} is a scalar, @var{a} and @var{b} must be of\n\
compatible dimensions.\n\
@end deftypefn")
{
  octave_value retval;

  int nargin = args.length ();

  if (nargin == 3)
    {
      octave_value x_arg = args(0);
      octave_value a_arg = args(1);
      octave_value b_arg = args(2);

      // FIXME Can we make a template version of the duplicated code below
      if (x_arg.is_single_type () || a_arg.is_single_type () ||
          b_arg.is_single_type ())
        {
          if (x_arg.is_scalar_type ())
            {
              float x = x_arg.float_value ();

              if (a_arg.is_scalar_type ())
                {
                  float a = a_arg.float_value ();

                  if (! error_state)
                    {
                      if (b_arg.is_scalar_type ())
                        {
                          float b = b_arg.float_value ();

                          if (! error_state)
                            retval = betainc (x, a, b);
                        }
                      else
                        {
                          FloatNDArray b = b_arg.float_array_value ();

                          if (! error_state)
                            retval = betainc (x, a, b);
                        }
                    }
                }
              else
                {
                  FloatNDArray a = a_arg.float_array_value ();

                  if (! error_state)
                    {
                      if (b_arg.is_scalar_type ())
                        {
                          float b = b_arg.float_value ();

                          if (! error_state)
                            retval = betainc (x, a, b);
                        }
                      else
                        {
                          FloatNDArray b = b_arg.float_array_value ();

                          if (! error_state)
                            retval = betainc (x, a, b);
                        }
                    }
                }
            }
          else
            {
              FloatNDArray x = x_arg.float_array_value ();

              if (a_arg.is_scalar_type ())
                {
                  float a = a_arg.float_value ();

                  if (! error_state)
                    {
                      if (b_arg.is_scalar_type ())
                        {
                          float b = b_arg.float_value ();

                          if (! error_state)
                            retval = betainc (x, a, b);
                        }
                      else
                        {
                          FloatNDArray b = b_arg.float_array_value ();

                          if (! error_state)
                            retval = betainc (x, a, b);
                        }
                    }
                }
              else
                {
                  FloatNDArray a = a_arg.float_array_value ();

                  if (! error_state)
                    {
                      if (b_arg.is_scalar_type ())
                        {
                          float b = b_arg.float_value ();

                          if (! error_state)
                            retval = betainc (x, a, b);
                        }
                      else
                        {
                          FloatNDArray b = b_arg.float_array_value ();

                          if (! error_state)
                            retval = betainc (x, a, b);
                        }
                    }
                }
            }
        }
      else
        {
          if (x_arg.is_scalar_type ())
            {
              double x = x_arg.double_value ();

              if (a_arg.is_scalar_type ())
                {
                  double a = a_arg.double_value ();

                  if (! error_state)
                    {
                      if (b_arg.is_scalar_type ())
                        {
                          double b = b_arg.double_value ();

                          if (! error_state)
                            retval = betainc (x, a, b);
                        }
                      else
                        {
                          NDArray b = b_arg.array_value ();

                          if (! error_state)
                            retval = betainc (x, a, b);
                        }
                    }
                }
              else
                {
                  NDArray a = a_arg.array_value ();

                  if (! error_state)
                    {
                      if (b_arg.is_scalar_type ())
                        {
                          double b = b_arg.double_value ();

                          if (! error_state)
                            retval = betainc (x, a, b);
                        }
                      else
                        {
                          NDArray b = b_arg.array_value ();

                          if (! error_state)
                            retval = betainc (x, a, b);
                        }
                    }
                }
            }
          else
            {
              NDArray x = x_arg.array_value ();

              if (a_arg.is_scalar_type ())
                {
                  double a = a_arg.double_value ();

                  if (! error_state)
                    {
                      if (b_arg.is_scalar_type ())
                        {
                          double b = b_arg.double_value ();

                          if (! error_state)
                            retval = betainc (x, a, b);
                        }
                      else
                        {
                          NDArray b = b_arg.array_value ();

                          if (! error_state)
                            retval = betainc (x, a, b);
                        }
                    }
                }
              else
                {
                  NDArray a = a_arg.array_value ();

                  if (! error_state)
                    {
                      if (b_arg.is_scalar_type ())
                        {
                          double b = b_arg.double_value ();

                          if (! error_state)
                            retval = betainc (x, a, b);
                        }
                      else
                        {
                          NDArray b = b_arg.array_value ();

                          if (! error_state)
                            retval = betainc (x, a, b);
                        }
                    }
                }
            }
        }
    }
  else
    print_usage ();

  return retval;
}

/*

%% test/octave.test/arith/betainc-1.m
%!test
%! a=[1, 1.5, 2, 3];
%! b=[4, 3, 2, 1];
%! v1=betainc(1,a,b);
%! v2=[1,1,1,1];
%! x = [.2, .4, .6, .8];
%! v3=betainc(x, a, b);
%! v4 = 1-betainc(1.-x, b, a);
%! assert(v1, v2, sqrt(eps));
%! assert(v3, v4, sqrt(eps));

%% Single precision
%!test
%! a=single ([1, 1.5, 2, 3]);
%! b=single ([4, 3, 2, 1]);
%! v1=betainc(1,a,b);
%! v2=single ([1,1,1,1]);
%! x = single ([.2, .4, .6, .8]);
%! v3=betainc(x, a, b);
%! v4 = 1-betainc(1.-x, b, a);
%! assert(v1, v2, sqrt(eps ('single')));
%! assert(v3, v4, sqrt(eps ('single')));

%% Mixed double/single precision
%!test
%! a=single ([1, 1.5, 2, 3]);
%! b=[4, 3, 2, 1];
%! v1=betainc(1,a,b);
%! v2=single ([1,1,1,1]);
%! x = [.2, .4, .6, .8];
%! v3=betainc(x, a, b);
%! v4 = 1-betainc(1.-x, b, a);
%! assert(v1, v2, sqrt(eps ('single')));
%! assert(v3, v4, sqrt(eps ('single')));

%% test/octave.test/arith/betainc-2.m
%!error <Invalid call to betainc> betainc();

%% test/octave.test/arith/betainc-3.m
%!error <Invalid call to betainc> betainc(1);

%% test/octave.test/arith/betainc-4.m
%!error <Invalid call to betainc> betainc(1,2);

*/