how can I eliminate this error

An installed compiler was not detected. Certain simulation modes, as well as host-based coder builds require that a compiler be installed. Please install one of the supported compilers for this release as listed at:

http://www.mathworks.com/support/compilers/R2013a/win64.html

[C.J. Harris]

Well that depends. Which compiler do you want to use to compile your code into an s-function?