Incomplete Objects
==================

When `(' or `[' is typed to begin entering a complex number or vector,
respectively, the effect is to push an "incomplete" complex number or
vector onto the stack.  The `,' key adds the value(s) at the top of
the stack onto the current incomplete object.  The `)' and `]' keys
"close" the incomplete object after adding any values on the top of
the stack in front of the incomplete object.

As a result, the sequence of keystrokes `[ 2 , 3 RET 2 * , 9 ]' pushes
the vector `[2, 6, 9]' onto the stack.  Likewise, `( 1 , 2 Q )' pushes
the complex number `(1, 1.414)' (approximately).

If several values lie on the stack in front of the incomplete object,
all are collected and appended to the object.  Thus the `,' key is
redundant: `[ 2 RET 3 RET 2 * 9 ]'.  Some people prefer the equivalent
SPC key to RET.

As a special case, typing `,' immediately after `(', `[', or `,' adds
a zero or duplicates the preceding value in the list being formed.
Typing DEL during incomplete entry removes the last item from the
list.

The `;' key is used in the same way as `,' to create polar complex
numbers: `( 1 ; 2 )'.  When entering a vector, `;' is useful for
creating a matrix.  In particular, `[ [ 1 , 2 ; 3 , 4 ; 5 , 6 ] ]' is
equivalent to `[ [ 1 , 2 ] , [ 3 , 4 ] , [ 5 , 6 ] ]'.

Incomplete entry is also used to enter intervals.  For example, `[ 2
.. 4 )' enters a semi-open interval.  Note that when you type the
first period, it will be interpreted as a decimal point, but when you
type a second period immediately afterward, it is re-interpreted as
part of the interval symbol.  Typing `..' corresponds to executing the
`calc-dots' command.

If you find incomplete entry distracting, you may wish to enter
vectors and complex numbers as algebraic formulas by pressing the
apostrophe key.