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(Radix modes): Mention twos-complement notation.

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Jay Belanger 2009-11-16 23:41:36 +00:00
parent 14467b99c9
commit 17291a1fc4
2 changed files with 41 additions and 1 deletions
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4
doc/misc/ChangeLog
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@ -1,3 +1,7 @@
2009-11-16 Jay Belanger <jay.p.belanger@gmail.com>
* calc.texi (Radix modes): Mention twos-complement notation.
2009-11-16 Juanma Barranquero <lekktu@gmail.com>
* makefile.w32-in (INFO_TARGETS, DVI_TARGETS, clean): Add semantic.

38
doc/misc/calc.texi
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@ -13173,6 +13173,42 @@ are displayed with at least enough digits to represent
in the current radix. (Larger integers will still be displayed in their
entirety.)
With the command @kbd{C-u d 2}, Calc will display integers using
twos-complement notation, using the current word-size to determine
the number of bits. When using twos-complement notation, a negative
word size might be appropriate (@pxref{Binary Functions}). If the
absolute value of the word size is @expr{w}, then twos-complement
notation will represent the integers in the symmetric interval from
@texline @math{-2^{w-1}}
@infoline @expr{-2^(w-1)}
to
@texline @math{2^{w-1}-1}
@infoline @expr{2^(w-1)-1}
using the binary numbers from @expr{0} to @expr{2^w}; the
integers from @expr{0} to
@texline @math{2^{w-1}-1}
@infoline @expr{2^(w-1)-1}
will be represented by their usual binary form and the integers
from
@texline @math{-2^{w-1}}
@infoline @expr{-2^(w-1)}
to @expr{-1} will be represented by first adding @expr{2^w} to them
and then using the usual binary form (so they will be represented by
the integers from
@texline @math{2^{w-1}}
@infoline @expr{2^(w-1)}
to @expr{2^w}). Calc will represent a twos-complement integer
by the radix @expr{2}, two @kbd{#} symbols, and the @expr{w} binary
digits (including any necessary leading zeros). Numbers that are not
displayed in twos-complement notation (i.e., that aren't integers from
@texline @math{-2^{w-1}}
@infoline @expr{-2^(w-1)}
to
@c (
@texline @math{2^{w-1}-1})
@infoline @expr{2^(w-1)-1})
will be represented using Calc's usual binary notation.
@node Grouping Digits, Float Formats, Radix Modes, Display Modes
@subsection Grouping Digits
@ -17969,7 +18005,7 @@ of the binary operations described here operate modulo @expr{2^w}. In
particular, negative arguments are converted to positive integers modulo
@expr{2^w} by all binary functions.
If the word size is negative, binary operations produce 2's complement
If the word size is negative, binary operations produce twos-complement
integers from
@texline @math{-2^{-w-1}}
@infoline @expr{-(2^(-w-1))}