function mean = reciprocal_mean ( a, b )

%*****************************************************************************80
%
%% reciprocal_mean() returns the mean of the Reciprocal PDF.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    20 September 2004
%
%  Author:
%
%    John Burkardt
%
%  Input:
%
%    real A, B, the parameters of the PDF.
%    0.0 < A <= B.
%
%  Output:
%
%    real MEAN, the mean of the PDF.
%
  mean = ( a - b ) / log ( a / b );

  return
end
