function cdf = gamma_cdf ( x, a, b, c )

%*****************************************************************************80
%
%% gamma_cdf() evaluates the Gamma CDF.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    27 March 2016
%
%  Author:
%
%    John Burkardt
%
%  Input:
%
%    real X, the argument of the PDF.
%    A <= X
%
%    real A, B, C, the parameters of the PDF.
%    0.0 < B,
%    0.0 < C.
%
%  Output:
%
%    real CDF, the value of the CDF.
%
  x2 = ( x - a ) / b;
  p2 = c;

  cdf = r8_gamma_inc ( p2, x2 );

  return
end
