PocketCAS is a free interface to the open-source Computer Algebra System giac/xcas.

xcas enables you to quickly solve complex algebraic problems, e.g. symbolic and numeric integration and derivation of non-trivial functions, solving differential equations etc. It has also a huge support for problems of linear algebra, like solving linear equation systems, multiplying and inverting matrices, finding eigenvalues (and eigenvectors, of course) and much more. If you do statistics or number theory, you will like xcas’ great functionality in those areas, too!

Changes:

Performance / Memory usage:
Minor optimizations regarding keyboard buildup. (should improve keyboard buildup time and reduce memory usage)
Compiled xcas and MimeTeX using the newest versions of cegcc and the corresponding libraries, but xcas is slightly outdated. (it is version 0.8.2, but it is not the newest build of it)
Improved speed of loading big history files and general speed of the UI very much. Text calculations now take as little as 60 milliseconds and TeX calculations take just 300 milliseconds!
Fixed memory leaks when switching into landscape mode.
Bug fixes:
Deleting the last remaining history element now clears the entire history (similar to File->New) rather than doing nothing.
The restart() function to purge all variables works properly now (patched xcas source – patch has already been merged into official xcas source).
findhelp also works now.
Keyboard changes:
Replaced some texts with appropriate mathematical symbols when inputting via keyboard. (Greek letters, differentials etc.)
Improved lots of the keyboard screens. Moved many buttons to other sections, created ‘Letters’ section and renamed ‘Helper’ to ‘Expr’ (Expression handling). The ‘Algebra’ section now contaisn real algebraic functions and commands like simplify, expand, etc. have been moved to ‘Expr’. Also moved xcas-specific commands (restart, purge, read, quote) to the 2nd screen.
Added a keyboard button (‘2nd’ section, where all xcas-specific commands are now) to read in files using xcas’ read() command (with file selection dialog included).
New features:
Added a menu entry to enable/disable downscaling for TeX output in History mode.
Added a menu entry to cut text snippets, next to copy and paste.
The last session will be loaded automatically upon start.
Package system has been changed. You will have to install two CABs (one Main Package and one Executable Package) on your device now. See Download page for details.

http://forum.xda-developers.com/showthread.php?t=415169