The commands for manipulating the Calc Trail buffer are two-key sequences beginning with the t prefix.
The t d
(calc-trail-display) command turns display of the
trail on and off. Normally the trail display is toggled on if it
was off, off if it was on. With a numeric prefix of zero, this
command always turns the trail off; with a prefix of one, it
always turns the trail on. The other trail-manipulation commands
described here automatically turn the trail on. Note that when
the trail is off values are still recorded there; they are simply
not displayed. To set Emacs to turn the trail off by default,
type t d and then save the mode settings with m
m (calc-save-modes).
The t i
(calc-trail-in) and t o
(calc-trail-out) commands switch the cursor into and
out of the Calc Trail window. In practice they are rarely used,
since the commands shown below are a more convenient way to move
around in the trail, and they work “by remote
control” when the cursor is still in the Calculator
window.
There is a trail pointer which selects some entry of the trail at any given time. The trail pointer looks like a ‘>’ symbol right before the selected number. The following commands operate on the trail pointer in various ways.
The t y
(calc-trail-yank) command reads the selected value
in the trail and pushes it onto the Calculator stack. It allows
you to re-use any previously computed value without retyping.
With a numeric prefix argument n, it yanks the value
n lines above the current trail pointer.
The t
< (calc-trail-scroll-left) and t
> (calc-trail-scroll-right) commands
horizontally scroll the trail window left or right by one half of
its width.
The t n
(calc-trail-next) and t p
(calc-trail-previous) commands move the trail
pointer down or up one line. The t f
(calc-trail-forward) and t b
(calc-trail-backward) commands move the trail
pointer down or up one screenful at a time. All of these commands
accept numeric prefix arguments to move several lines or
screenfuls at a time.
The t [
(calc-trail-first) and t ]
(calc-trail-last) commands move the trail pointer to
the first or last line of the trail. The t h
(calc-trail-here) command moves the trail pointer to
the cursor position; unlike the other trail commands, t
h works only when Calc Trail is the selected window.
The
t s (calc-trail-isearch-forward) and
t r (calc-trail-isearch-backward)
commands perform an incremental search forward or backward
through the trail. You can press <RET> to terminate the
search; the trail pointer moves to the current line. If you
cancel the search with C-g, the trail pointer stays
where it was when the search began.
The t m
(calc-trail-marker) command allows you to enter a
line of text of your own choosing into the trail. The text is
inserted after the line containing the trail pointer; this
usually means it is added to the end of the trail. Trail markers
are useful mainly as the targets for later incremental searches
in the trail.
The t k
(calc-trail-kill) command removes the selected line
from the trail. The line is saved in the Emacs kill ring suitable
for yanking into another buffer, but it is not easy to yank the
text back into the trail buffer. With a numeric prefix argument,
this command kills the n lines below or above the
selected one.
The t . (calc-full-trail-vectors)
command is described elsewhere; see Vector
and Matrix Formats.