"Any idea how to get the "7.0" number from the file/meta data?"
In general this is impossible... for the simple reason that the 5.0 MAT files can be exactly identical depending on the options used when saving. For example, both SAVE options -v6 and -v7 -nocompression produce exactly the same files (scroll right to view the data):
X = pi;
save testv4.mat X -v4
save testv6.mat X -v6
save testv7.mat X -v7 -nocompression
save testv73.mat X -v7.3 -nocompression
type testv4.mat
type testv6.mat
type testv7.mat
type testv73.mat
So the flags -v6 and -v7 -nocompression can generate 5.0 MAT files which may be bit identical, i.e. which flag was used when SAVEing is not determinable from the file data alone:
tv6 = fileread('testv6.mat');
tv7 = fileread('testv7.mat');
isequal(tv6,tv7)
In a sense, SAVE's VERSION option is a misnomer: it is really a supported feature flag to enable different supported features when saving the files (e.g. Unicode, compression), rather than any specific differences in the file format itself. See also:
And if you really want to understand the 4.0 and 5.0 MAT file formats:
