Caches
------

Calc saves certain values after they have been computed once.  For
example, the `P' (`calc-pi') command initially "knows" the constant
`pi' to about 20 decimal places; if the current precision is greater
than this, it will recompute `pi' using a series approximation.  This
value will not need to be recomputed ever again unless you raise the
precision still further.  Many operations such as logarithms and sines
make use of similarly cached values such as `pi/4' and `ln(2)'.  The
visible effect of caching is that high-precision computations may seem
to do extra work the first time.  Other things cached include powers
of two (for the binary arithmetic functions), matrix inverses and
determinants, symbolic integrals, and data points computed by the
graphing commands.

If you suspect a Calculator cache has become corrupt, you can use the
`calc-flush-caches' command to reset all caches to the empty state.
(This should only be necessary in the event of bugs in the
Calculator.)  The `M-# 0' (with the zero key) command also resets
caches along with all other aspects of the Calculator's state.