calc: Stack Manipulation
6.1 Stack Manipulation Commands
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To duplicate the top object on the stack, press <RET> or <SPC> (two
equivalent keys for the ‘calc-enter’ command). Given a positive numeric
prefix argument, these commands duplicate several elements at the top of
the stack. Given a negative argument, these commands duplicate the
specified element of the stack. Given an argument of zero, they
duplicate the entire stack. For example, with ‘10 20 30’ on the stack,
<RET> creates ‘10 20 30 30’, ‘C-u 2 <RET>’ creates ‘10 20 30 20 30’,
‘C-u - 2 <RET>’ creates ‘10 20 30 20’, and ‘C-u 0 <RET>’ creates ‘10 20
30 10 20 30’.
The <LFD> (‘calc-over’) command (on a key marked Line-Feed if you
have it, else on ‘C-j’) is like ‘calc-enter’ except that the sign of the
numeric prefix argument is interpreted oppositely. Also, with no prefix
argument the default argument is 2. Thus with ‘10 20 30’ on the stack,
<LFD> and ‘C-u 2 <LFD>’ are both equivalent to ‘C-u - 2 <RET>’,
producing ‘10 20 30 20’.
To remove the top element from the stack, press <DEL> (‘calc-pop’).
The ‘C-d’ key is a synonym for <DEL>. (If the top element is an
incomplete object with at least one element, the last element is removed
from it.) Given a positive numeric prefix argument, several elements
are removed. Given a negative argument, the specified element of the
stack is deleted. Given an argument of zero, the entire stack is
emptied. For example, with ‘10 20 30’ on the stack, <DEL> leaves ‘10
20’, ‘C-u 2 <DEL>’ leaves ‘10’, ‘C-u - 2 <DEL>’ leaves ‘10 30’, and ‘C-u
0 <DEL>’ leaves an empty stack.
The ‘M-<DEL>’ (‘calc-pop-above’) command is to <DEL> what <LFD> is to
<RET>: It interprets the sign of the numeric prefix argument in the
opposite way, and the default argument is 2. Thus ‘M-<DEL>’ by itself
removes the second-from-top stack element, leaving the first, third,
fourth, and so on; ‘M-3 M-<DEL>’ deletes the third stack element.
The above commands do not depend on the location of the cursor. If
the customizable variable ‘calc-context-sensitive-enter’ is non-‘nil’
(
Customizing Calc), these commands will become context
sensitive. For example, instead of duplicating the top of the stack,
<RET> will copy the element at the cursor to the top of the stack. With
a positive numeric prefix, a copy of the element at the cursor and the
appropriate number of preceding elements will be placed at the top of
the stack. A negative prefix will still duplicate the specified element
of the stack regardless of the cursor position. Similarly, <DEL> will
remove the corresponding elements from the stack.
To exchange the top two elements of the stack, press <TAB>
(‘calc-roll-down’). Given a positive numeric prefix argument, the
specified number of elements at the top of the stack are rotated
downward. Given a negative argument, the entire stack is rotated
downward the specified number of times. Given an argument of zero, the
entire stack is reversed top-for-bottom. For example, with ‘10 20 30 40
50’ on the stack, <TAB> creates ‘10 20 30 50 40’, ‘C-u 3 <TAB>’ creates
‘10 20 50 30 40’, ‘C-u - 2 <TAB>’ creates ‘40 50 10 20 30’, and ‘C-u 0
<TAB>’ creates ‘50 40 30 20 10’.
The command ‘M-<TAB>’ (‘calc-roll-up’) is analogous to <TAB> except
that it rotates upward instead of downward. Also, the default with no
prefix argument is to rotate the top 3 elements. For example, with ‘10
20 30 40 50’ on the stack, ‘M-<TAB>’ creates ‘10 20 40 50 30’, ‘C-u 4
M-<TAB>’ creates ‘10 30 40 50 20’, ‘C-u - 2 M-<TAB>’ creates ‘30 40 50
10 20’, and ‘C-u 0 M-<TAB>’ creates ‘50 40 30 20 10’.
A good way to view the operation of <TAB> and ‘M-<TAB>’ is in terms
of moving a particular element to a new position in the stack. With a
positive argument N, <TAB> moves the top stack element down to level N,
making room for it by pulling all the intervening stack elements toward
the top. ‘M-<TAB>’ moves the element at level N up to the top.
(Compare with <LFD>, which copies instead of moving the element in level
N.)
With a negative argument -N, <TAB> rotates the stack to move the
object in level N to the deepest place in the stack, and the object in
level N+1 to the top. ‘M-<TAB>’ rotates the deepest stack element to be
in level N, also putting the top stack element in level N+1.
Selecting Subformulas, for a way to apply these commands to
any portion of a vector or formula on the stack.
The command ‘C-x C-t’ (‘calc-transpose-lines’) will transpose the
stack object determined by the point with the stack object at the next
higher level. For example, with ‘10 20 30 40 50’ on the stack and the
point on the line containing ‘30’, ‘C-x C-t’ creates ‘10 20 40 30 50’.
More generally, ‘C-x C-t’ acts on the stack objects determined by the
current point (and mark) similar to how the text-mode command
‘transpose-lines’ acts on lines. With argument N, ‘C-x C-t’ will move
the stack object at the level above the current point and move it past N
other objects; for example, with ‘10 20 30 40 50’ on the stack and the
point on the line containing ‘30’, ‘C-u 2 C-x C-t’ creates ‘10 40 20 30
50’. With an argument of 0, ‘C-x C-t’ will switch the stack objects at
the levels determined by the point and the mark.
Info Catalog
calc: Stack and Trail
calc: Stack and Trail
calc: Editing Stack Entries