Calca takes ideas from Soulver and super sizes them:

* Soulver allows free text editing within a line of computation; Calca allows free editing in the entire file

* Both update as you type

* Soulver understands arithmetic; Calca knows algebra, calculus, and algorithms

* Soulver requires that all variables be defined; Calca does not

* Soulver does not support user defined functions; to Calca, everything is a function

* Soulver has no programming constructs; Calca is one step away from being a general purpose programming language.

* Soulver does not support matrices; Calca does