matlab错误提示： Warning: Variable 'a' cannot be saved to a MAT-file whose version is older than 7.3.

save mat文件的时候出现错误：
matlab错误提示：
Warning: Variable 'a' cannot be saved to a MAT-file whose versionis older than 7.3.To save this variable, use the -v7.3 switch.****Skipping...

解决办法：
打开matlab，file/preferences，general选项卡-MAT-Files,选择第一个。

save -v7.3 TrainData.mat trainPatches
参考网址：http://blog.csdn.net/yihaizhiyan/article/details/14133835