m_colmap函数用于创建和管理颜色映射（colormap）。颜色映射可以用来对数据进行可视化编码，例如在地图上显示温度、高度、速度等信息。
m_colmap函数的一般形式如下：
cols=m_colmap(nme,m,ncol)
% m_colmap Useful colormaps
% m_colmap(NAME) returns an M-by-3 matrix containing the NAME colormap
% where NAME is one of:
% 'jet' : a perceptually uniform variation of the JET colormap. It
% contains the multiple colours which make JET useful, while
% avoiding the weird highlighting especially around yellow and
% cyan. The colors begin with dark blue, range through shades
% of blue, green, orange and red, and ends with dark red.
% 'mBOD' : a modified blue/orange diverging colormap without white,
% useful as a colorblind-friendly jet alternative
%
% 'diverging' : a blue/red diverging colormap
% 'BOD' : a blue/orange diverging colormap
% 'rBOD' : a different blue/orange colormap with gray in the middle
%
% 'odv' : an isoluminant map
% 'cyclic2': a cyclic colormap (for angles) with two dark regions
% 'cyclic1': a cyclic colormap (for angles) with one dark region
%
% 'land' : a topographic height (green-brown-white) shading
% 'water' : blue shading for water (goes with 'land').
% 'gland' : a topographic height shading with more green
% 'bland' : a topographic height shading with browns only.
%
% 'blue' : a perceptually useful blue shading (good for bathymetry)
% 'green' : a perceptually useful green shading
% 'chlorophyll': Enhanced green for chlorophyll (to red)
% 'CBchlorophyll': Enhanced green for chlorophyll (to magenta)
% <-colorblind friendly
%
% 'EK80' : a standard echo-sounder map.
% 'chart': the standard chart colour (single color)
%
% and M is the same length as the current figure's colormap. If no
% figure exists, the length of the default colormap is used. The
% length can be explicitly specified with s_colmap(NAME,M).
%
% m_colmap('demo') demonstrates the colormaps.
%
% m_colmap(NAME,'step') returns a 256-color map in which colours are
% perceptually bunched into 16 separate colours. This is useful
% if you want to see "edges" in what would be an otherwise
% smooth gradation (i.e. approaching the look of contouring).
%
% m_colmap(NAME,'demo') Gives a demo of this behavior
%
% m_colmap(NAME,'step',M) bunches into M colours.
其中，nme 选择一种颜色类型；m 颜色长度，不设置就自动用默认的，设置了就颜色条按区间进行分段；
m_map的所有颜色类型可以通过下面一句代码查看：
m_colmap demo
m_colmap函数的使用示例，示例数据可以从网盘获取，提取码：ofxi：
%% m_colormap
clc;clear;
ncFilePath = 'GLDAS_NOAH10_M.A200602.021.nc4';
lon = ncread(ncFilePath,'lon');
lat = ncread(ncFilePath,'lat');
soilmoi_data = ncread(ncFilePath,'SoilMoi0_10cm_inst');
[LN,LT]=meshgrid(lon,lat);
m_proj('mercator','long',[69.5 105.5],'lat',[24.5 40.5]);
% 在地图上绘制伪彩色图
m_pcolor(LN,LT, soilmoi_data');
colormap( m_colmap('jet') );
%colormap( m_colmap('jet',10) );
% 添加地图边界、标签和色标
m_gshhs('ic','color',[.5 .5 .5]) % 中等分辨率海岸线
m_gshhs('ir2','color','k') % 中等分辨率河流
m_grid('linestyle','none','tickdir','out');
colorbar;
对比下图可以发现，绘制在图右侧的颜色调划分上存在差异，这就是设置了m的差别，根据需要选择合适的命令参数，能够绘出更加符合的图示：
 |
 |