For linear systems, see Matrix.solv.
prmat
Prints the form of the matrix defined by eqn <keyword_eqn> statements. Each nonzero element is printed as an "*".
solve
Does one iteration of the non-linear system defined by eqn <keyword_eqn> statements. Returns the linear norm of the difference between left and right hand sides plus the change in the dependent variables.
eqinit
Throws away previous dependent variable and equation specifications from eqn <keyword_eqn> statements.