Isotherms computation

This function computes isotherm from gridded data set as well as profile datas

% It is constant temperature depth. i.e. 20 deg. C isotherm defines depth at which temperature
% is 20C, often denoted as Z20 or D20
%===========================================================%
% RA_ISOTHERM $Id: ra_isotherm.m, 2015/02/20 $
% Copyright (C) CORAL-IITKGP, Ramkrushn S. Patel 2014.
%
% AUTHOR:
% Ramkrushn S. Patel ([e-mail])
% Roll No: 13CL60R05
% Place: IIT Kharagpur.
% This is a part of M. Tech project under the supervision of DR. ARUN CHAKRABORTY
%===========================================================%
%
% USAGE: isotherm=ra_isotherm(temp,Z,isovalue)
%
% DESCRIPTION: This function determines Isotherms from profile data sets. If you have 3D
% data sets i.e. level, lat and lon and want to compute the Isotherm, then this function will
% be very handy. Because this function is specifically designed for those cases. However,
% it can evaluate isotherms from profile data too.
%
% INPUTS:
% temp = Temperature profiles over the study region [deg. C], either 3D or vector
% Z = Levels [m], Must be vector
% isovalue = temperature at which you want to compute isotherms [deg. C], Must be scalar
%
% OUTPUT:
% isotherm = Isotherms depth, spatial output [m]