HomalgToCAS is one of the core packages of the homalg project [hpa10]. 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 homalg: The Core Packages and the Idea behind their Splitting of the homalg package manual (--> homalg: HomalgToCAS):
"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."
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
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