You can put more than one function in a file, but the additional functions will only be directly visible to the first function in that file. In order for any outside file to be able to invoke the additional functions, the outside file would need to have access to a function handle for the routine.
One way that you can arrange this is something like,
function funstruct = calculus_library
funstruct.differentiate_polynomial = @diffpoly;
funstruct.integrate_polynomial = @intpoly;
funstruct.differentiate_trig = @difftrig;
end
function r = diffpoly(....)
[...]
function r = difftrig(....)
[...]
That is, make the main routine for the file one that you can call on to retrieve the function handle you are interested in.
