API for mathematical calculations on the cloud

Is there any service that provide a public API to perform mathematical calculations (such as linear algebra decompositions etc)?

Thanks

I've created a Java Google Appengine based service here mobmath.appspot.com. You can find the project page here: Symja project. The Linear Algebra functions are implemented with the commons math library (Examples).

There exist a project for Python here: Sympy project the online interface can be found here: live.sympy.org.

Wolfram Alpha has an API, but it isn't free to use.