A script file is a text file that contains a sequence of
Shang commands. For example, a file with name "testscript.txt" may contain
the following lines
f = (h, r, theta) -> r^2 + h * (1 + cos(theta));
h = 3.5;
r = 5;
theta = pi / 2;
f(h, r, theta)
In the interactive mode, if the following command is issued
>> run("testscript.txt");
28.5
>>
All the commands in the script file will be executed.