Computer Algebra systems, new trends

Computer Algebra systems (CAS for short) are softwares for doing symbolic mathematics. Such software includes graphics, elaborate user interfaces and numeric program as well as algorithms for symbolic computation. Notable results have been achieved in symbolic computation in the last two decades and CAS have improved the productivity of scientists and engineers. A typicall CAS is often large and exceedingly complex, requiring many person-years to implement, document, maintain and upgrade. They are several challenges for CAS designers. One example is to find techniques to modularize the software development process so that it can be done in smaller parts. Another example is to provide visual means for extracting or replacing parts of symbolic expressions, moving terms around, cancelling and doing other manipulations. To meet these challenges, the computer science of symbolic computation exhibits a variety of techniques beyond those of numerical computation: complex data structures, ob ject-oriented programming style and number of other advanced programming tools are used. We are presenting in this paper some of the new software techniques used in modern CAS design.