The -ASCII option saves a double array as a text file with space delimiters. This means:
- Any text editor can open that text file.
- Any application that can parse a text file containing numeric data separated with (multiple) space character delimiters can import that data.
The MS Excel file importing wizard also handles it without any problems.
As Guillaume pointed out, you should probably avoid using save anyway: its text file format is apparently designed to look nice for humans and not really for transferring data between applications.