存.mat文件时出错：Warning: Variable 'a' cannot be saved to a MAT-file whose version is older than 7.3.

存.mat文件时出现错误如下：

matlab错误提示：

Warning: Variable 'feature' cannot be saved to a MAT-file whose version

is older than 7.3.

To save this variable, use the -v7.3 switch.

Skipping...

解决办法：

打开matlab，preferences，general选项卡-MAT-Files,选择第一个。

如下图所示：