This is quite interesting! I could do it this way:
Suppose a file called data has the lines:
x = 5;
y = (x^2+x)*cos(x);
Now you can read the file data as is using
z = textread('data','%s');
and with a quick conversion into a string using
y = cell2mat(z') %transpose to get the data in a row rather than a column, for z is a column of cells.
do an eval(y) to evaluate the contents of the textfile!
