说明：  本程序为matlab编写。已知海水深度、海底水温和地热梯度，根据天然气水合物存在的温压条件，求取天然气水合物是否存在，若存在，求出其厚度。
(This program is written in matlab. Known water depth, water temperature and geothermal gradient seabed, according to the presence of gas hydrate temperature and pressure conditions, to strike a gas hydrate exists, if present, determine its thickness.)