Solving Equations
=================

The `a S' (`calc-solve-for') [`solve'] command rearranges an equation
to solve for a specific variable.  An equation is an expression of the
form `L = R'.  For example, the command `a S x' will rearrange `y = 3x
+ 6' to the form, `x = y/3 - 2'.  If the input is not an equation, it
is treated like an equation of the form `X = 0'.

This command also works for inequalities, as in `y < 3x + 6'.
Some inequalities cannot be solved where the analogous equation could
be; for example, solving `a < b c' for `b' is impossible
without knowing the sign of `c'.  In this case, `a S' will
produce the result `b != a/c' (using the not-equal-to operator)
to signify that the direction of the inequality is now unknown.  The
inequality `a <= b c' is not even partially solved.
See Declarations, for a way to tell Calc that the signs of the
variables in a formula are in fact known.

Two useful commands for working with the result of `a S' are `a .' 
(See Logical Operations), which converts `x = y/3 - 2' to `y/3 -
2', and `s l' (See Let Command) which evaluates another formula
with `x' set equal to `y/3 - 2'.

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Multiple Solutions

Solving Systems of Equations

Decomposing Polynomials