In pre-3.4 versions of REDUCE the display of derivatives of functional forms (i.e. things declared with the depend() command) was somewhat dull. A quick fix was made in REDTEN to allow these forms to display as, for example,
#: depend f,r$
#: df(f,r);
f
r
rather than
#: df(f,r); df(f,r)In REDUCE 3.4 a very similar package exists, controlled by the switch dfprint, which has been turned on in REDTEN.
In addition, to handle the display of certain constructs that can appear in REDTEN (derivatives with respect to coordinate vectors), another display package has been introduced for this case. If the switch fancydf[off] is on, then this package is used for all derivatives of functional forms. The format is of a fraction involving differentials, with the appropriate degrees located in the conventional places.
#: df (f,x[a]); % note f must depend on at least one coordinate.
d f
-------
a
d x
#: on fancydf$
#: df(f,r,r);
2
d f
------
2
d r
A minor enhancement is obtained when the switch bell
is turned on, in this case the terminal bell is sounded after every
prompt. The only use for this is to notify the user at the end of a
long calculation, at other times the bell is annoying.
To enable easier timing of the entire process of evaluating a metric family, two new timing functions have been added to REDTEN. To start the timer the function stime() can be called; the elapsed CPU time since the last call to this function is returned by the function etime(). The timer is not reset by etime(), so it can be called many times in succession, and will show progressively larger elapsed times until a new call to stime() is made.