doc/eval: fix/review the section about SI prefixes and usage

In particular, prefer "prefix" to "postfix" as in the tool manuals, and
specify powers of 2 and 10 explicitly.

This is based on the commit:
commit 2bf794b698
Author: Marcus Stollsteimer <sto.mar@web.de>
Date:   Mon Nov 19 21:39:20 2012 +0100
pull/9/head
Stefano Sabatini 12 years ago
parent ca1bc188f4
commit c89a8ee23d
  1. 55
      doc/eval.texi

@ -209,55 +209,56 @@ In your C code, you can extend the list of unary and binary functions,
and define recognized constants, so that they are available for your
expressions.
The evaluator also recognizes the International System number
postfixes. If 'i' is appended after the postfix, powers of 2 are used
instead of powers of 10. The 'B' postfix multiplies the value for 8,
and can be appended after another postfix or used alone. This allows
using for example 'KB', 'MiB', 'G' and 'B' as postfix.
Follows the list of available International System postfixes, with
The evaluator also recognizes the International System unit prefixes.
If 'i' is appended after the prefix, binary prefixes are used, which
are based on powers of 1024 instead of powers of 1000.
The 'B' postfix multiplies the value by 8, and can be appended after a
unit prefix or used alone. This allows using for example 'KB', 'MiB',
'G' and 'B' as number postfix.
The list of available International System prefixes follows, with
indication of the corresponding powers of 10 and of 2.
@table @option
@item y
-24 / -80
10^-24 / 2^-80
@item z
-21 / -70
10^-21 / 2^-70
@item a
-18 / -60
10^-18 / 2^-60
@item f
-15 / -50
10^-15 / 2^-50
@item p
-12 / -40
10^-12 / 2^-40
@item n
-9 / -30
10^-9 / 2^-30
@item u
-6 / -20
10^-6 / 2^-20
@item m
-3 / -10
10^-3 / 2^-10
@item c
-2
10^-2
@item d
-1
10^-1
@item h
2
10^2
@item k
3 / 10
10^3 / 2^10
@item K
3 / 10
10^3 / 2^10
@item M
6 / 20
10^6 / 2^20
@item G
9 / 30
10^9 / 2^30
@item T
12 / 40
10^12 / 2^40
@item P
15 / 40
10^15 / 2^40
@item E
18 / 50
10^18 / 2^50
@item Z
21 / 60
10^21 / 2^60
@item Y
24 / 70
10^24 / 2^70
@end table
@c man end

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