what are built-in functions?

I wanted to see the code of svd, but when I type edit svd.m I get a description of the code and a comment saying Built-in function. What does this exactly mean? That svd is written directly in C?

Answer 1

[Laura Proctor]

From the doc:

Functions that are frequently used or that can take more time to execute are often implemented as executable files. These functions are called built-ins.

Unlike MATLAB program file functions, you cannot see the source code for built-ins. Although most built-in functions do have a program file associated with them, this file is there mainly to supply the help documentation for the function.

http://www.mathworks.com/access/helpdesk/help/techdoc/matlab_prog/br65lhj-1.html#br65lhj-6

Answer 2

[John D'Errico]

Yes. You can't see that code, as it does not exist in the form of m-code. Only the help is available, but MATLAB knows to use the compiled version. Usually this is to improve the speed.

Answer 3

[Andrew Newell]

A lot of MATLAB builtins are based on LAPACK. You might find this post interesting.