I have Matlab on Windows 7 and I need to use it in my Ubuntu system installed on Virtualbox because I am working on files only compatible in Linux. How can I transfer Matlab into my Ubuntu system?
"files only compatible in Linux"
What do yo mean ? Like all the lines are separated by a LF instead of a CRLF ? You can find converters for that. There should be a way to make your files compatible with Windows, installing Ubuntu to solve a compatibility issue looks stupid.
You should ask for help porting the Matlab files on GNU/Linux to Matlab on Windows instead.
Programs cannot generally be "transferable" from one computer to another. Particularly between operating systems, this just isn't possible. The installation and un-installation processes are just not comparable. You can install on Ubuntu but this is separate from Uninstalling on Windows. It may look like the same software to you, but it's not the same program underneath the hood. The except to this is what are called "Portable Apps", which are bundled together with all the files needed for various platforms and made to run without installing. See http://portableapps.com for some samples of this.
What I recommend is setting up a shared-file space between Linux and Windows. You can do this fairly easily with VirtualBox's tools so that the guest can easily mount a folder from the host as a network drive.
Once you have file sharing worked out so your Ubuntu guest can write files to a folder where your Windows Matlab can access, you can use Linux tools to easily convert files between Unix and Windows formats. The only difference is the line-endings. Several tools are available to do this, the two easiest to figure out are
unix2dos. You can probably guess which one is which. You could convert your files from one format to the other like this:
unix2dos unix_data_file.txt windows_data_file.txt
(I'm sure matlab uses something other than
.txt extensions but if the problem is unix vs Linux formats they are almost certainly just text files, so use whatever filenames you have, and just write a converted one to be used on Windows.)
See https://help.ubuntu.com/community/MATLAB for installing matlab on ubuntu