function value = tan_cordic ( beta, n )

%*****************************************************************************80
%
%% TAN_CORDIC returns the tangent of an angle using the CORDIC method.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    15 June 2007
%
%  Author:
%
%    Based on MATLAB code in a Wikipedia article.
%
%    Modifications by John Burkardt
%
%  Parameters:
%
%    Input, real BETA, the angle (in radians).
%
%    Input, integer N, the number of iterations to take.
%    A value of 10 is low.  Good accuracy is achieved with 20 or more
%    iterations.
%
%    Output, real VALUE, the tangent of the angle.
%
%  Local Parameters:
%
%    Local, real ANGLES(60) = arctan ( (1/2)^(0:59) );
%
  angles = [  ...
    7.8539816339744830962E-01, ...
    4.6364760900080611621E-01, ...
    2.4497866312686415417E-01, ...
    1.2435499454676143503E-01, ...
    6.2418809995957348474E-02, ...
    3.1239833430268276254E-02, ...
    1.5623728620476830803E-02, ...
    7.8123410601011112965E-03, ...
    3.9062301319669718276E-03, ...
    1.9531225164788186851E-03, ...
    9.7656218955931943040E-04, ...
    4.8828121119489827547E-04, ...
    2.4414062014936176402E-04, ...
    1.2207031189367020424E-04, ...
    6.1035156174208775022E-05, ...
    3.0517578115526096862E-05, ...
    1.5258789061315762107E-05, ...
    7.6293945311019702634E-06, ...
    3.8146972656064962829E-06, ...
    1.9073486328101870354E-06, ...
    9.5367431640596087942E-07, ...
    4.7683715820308885993E-07, ...
    2.3841857910155798249E-07, ...
    1.1920928955078068531E-07, ...
    5.9604644775390554414E-08, ...
    2.9802322387695303677E-08, ...
    1.4901161193847655147E-08, ...
    7.4505805969238279871E-09, ...
    3.7252902984619140453E-09, ...
    1.8626451492309570291E-09, ...
    9.3132257461547851536E-10, ...
    4.6566128730773925778E-10, ...
    2.3283064365386962890E-10, ...
    1.1641532182693481445E-10, ...
    5.8207660913467407226E-11, ...
    2.9103830456733703613E-11, ...
    1.4551915228366851807E-11, ...
    7.2759576141834259033E-12, ...
    3.6379788070917129517E-12, ...
    1.8189894035458564758E-12, ...
    9.0949470177292823792E-13, ...
    4.5474735088646411896E-13, ...
    2.2737367544323205948E-13, ...
    1.1368683772161602974E-13, ...
    5.6843418860808014870E-14, ...
    2.8421709430404007435E-14, ...
    1.4210854715202003717E-14, ...
    7.1054273576010018587E-15, ...
    3.5527136788005009294E-15, ...
    1.7763568394002504647E-15, ...
    8.8817841970012523234E-16, ...
    4.4408920985006261617E-16, ...
    2.2204460492503130808E-16, ...
    1.1102230246251565404E-16, ...
    5.5511151231257827021E-17, ...
    2.7755575615628913511E-17, ...
    1.3877787807814456755E-17, ...
    6.9388939039072283776E-18, ...
    3.4694469519536141888E-18, ...
    1.7347234759768070944E-18 ];
%
%  Shift angle to interval [-pi,pi].
%
  theta = angle_shift ( beta, -pi );
%
%  Shift angle to interval [-pi/2,pi/2] and account for signs.
%
  if ( theta < - 0.5 * pi )
    theta = theta + pi;
  elseif ( 0.5 * pi < theta )
    theta = theta - pi;
  end

  v = [ 1.0; 0.0 ];
  poweroftwo = 1.0;
  angle = angles(1);

  for j = 1 : n

    if ( theta < 0.0 )
      sigma = -1.0;
    else
      sigma = +1.0;
    end

    factor = sigma * poweroftwo;

    R = [ 1.0,   -factor;...
          factor, 1.0      ];

    v = R * v;
%
%  Update the remaining angle.
%
    theta = theta - sigma * angle;

    poweroftwo = poweroftwo / 2.0;
%
%  Update the angle from table, or eventually by just dividing by two.
%
    if ( length ( angles ) < ( j + 1 ) )
      angle = angle / 2.0;
    else
      angle = angles(j+1);
    end

  end

  value = v(2) / v(1);

  return
end
