1.  NAME

  rho - Calculate sigma or sigma-theta

  2.  SYNOPSIS

  s = rho(T, S )

  3.  DESCRIPTION

  Calculates density anomally sigma or theta sigma.

  This function was called rho and not sigma because there is already a
  sigma function in Matlab.

  4.  PARAMETERS

     P  Vector of pressure (in dbar).

     T  Vector of temperature or potential temperature (in deg C).

     S  Vector of salinity (in ppm).

  5.  RETURNS

     s  Sigma (in kg/m^3) relative to 1000.0 kg/m^3.

  6.  AUTHORS

  Pierre Jaccard, Geophysical Institute, University of Bergen, 1999