saving image with 'print' using specified width but maintaining aspect ratio

I want to save an image using the 'print' command by passing it a width (say 6.0 inches) but want to retain the aspect ratio. How can I do this? The help page only gives me two options: save at the same size as the figure window or use the 'fillpage' option, neither of which are useful for my purpose.

Any help is appreciated.

[Jess Lovering]

I have had more luck with exporting graphics using the export_fig function that is on Matlab Central. It has some more options and controls. You may want to check it out.

https://www.mathworks.com/matlabcentral/fileexchange/23629-export_fig