Problem to save a variable to a .mat file

When I try to save my workspace i got this message

Warning: Variable 'Colunas2D' cannot be saved to
a MAT-file whose version is older than 7.3.
To save this variable, use the -v7.3 switch.
Skipping...

How can I save this variable into a .mat file Thank you

Answer 1

[José-Luis]

The error message is descriptive. Please try:

 save(filename,variables,'-v7.3')

Please read the documentation if you would like to understand better:

 doc save

Answer 2

[Image Analyst]

You can delete that old, pre-v7.3 mat file, and just save it anew.