Introduction &HomalgToCAS; is one of the core packages of the &homalg; project . But as one of the rather technical packages, this manual is probably not of interest for the average uers. The average user will usually not get in direct contact with the operations provided by this package.

Quoting from the Appendix of the &homalg; package manual (&see; ):

The package &HomalgToCAS; (which needs the &homalg; package) includes all what is needed to let the black boxes used by &homalg; reside in external computer algebra systems. So as mentioned above, &HomalgToCAS; is the right place to declare the three &GAP; representations external rings, external ring elements, and external matrices. Still, &HomalgToCAS; is independent from the external computer algebra system with which &GAP; will communicate and independent of how this communication physically looks like.
&HomalgToCAS; provides ... Declaration and construction of external objects (which are pointers to data (rings,ring elements, matrices, ...) residing in external systems) external rings (as a new representation for the &GAP4;-category of homalg rings) external ring elements (as a new representation for the &GAP4;-category of homalg ring elements) external matrices (as a new representation for the &GAP4;-category of homalg matrices) LaunchCAS: the standard interface used by &homalg; to launch external systems TerminateCAS: the standard interface used by &homalg; to terminate external systems homalgSendBlocking: the standard interface used by &homalg; to send commands to external systems External garbage collection: delete the data in the external systems that became obsolete for &homalg; homalgIOMode: decide how much of the communication you want to see