function value = sincu_deriv2 ( x )

%*****************************************************************************80
%
%% sincu_deriv2(): second derivative of the unnormalized sinc() function.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    26 March 2025
%
%  Author:
%
%    John Burkardt
%
%  Input:
%
%    real x: the argument of the function.
%
%  Output:
%
%    real value, the value of the second derivative.
%
  value = zeros ( size ( x ) );

  nz = find ( x ~= 0.0 );
  zr = find ( x == 0.0 );

  value(nz) = ...
    ( ( 2.0 - x(nz).^2 ) .* sin ( x(nz) ) ...
    - 2.0 * x(nz) .* cos ( x(nz) ) ) ./ x(nz).^3;
  value(zr) = - 1.0 / 3.0;

  return
end

