r8_cube_root <- function ( x )

#*****************************************************************************80
#
## r8_cube_root() returns the cube root of an R8.
#
#  Discussion:
#
#    This routine is designed to avoid the possible problems that can occur
#    when formulas like 0.0^(1/3) or (-1.0)^(1/3) are to be evaluated.
#
#  Licensing:
#
#    This code is distributed under the MIT license. 
#
#  Modified:
#
#    12 May 2021
#
#  Author:
#
#    John Burkardt
#
#  Input:
#
#    real X, the number whose cube root is desired.
#
#  Output:
#
#    real VALUE, the cube root of X.
#
{
  xnrm = abs ( x )

  if ( x < 0.0 )
  {
    s = -1.0
  }
  else
  {
    s = +1.0
  }

  p = 1.0 / 3.0

  value = s * ( xnrm ^ p )

  return ( value )
}