Delila Program: logscale
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logscale program

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Documentation for the logscale program is below,
with links to related programs in the "see also" section.

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**{ version = 1.02; (* of logscale.p 2010 Sep 18}
(* begin module describe.logscale *)
(*
name
logscale: provide numbers on a log scale
synopsis
logscale(input: in, output: out)
files
input: one line with the following values:
x (real): starting value
b (integer): base of the scale (eg 2 or 10)
n (integer): number of intervals
If n is negative, report the program version number.
m (integer): which interval we are on
w (integer): width of output number (characters)
d (integer): decimal places of output number (characters)
output: messages to the user
description
Create numbers on a log scale one at a time for use in scripts.
Let the scale look like this (where b = 10):
x * z * z * z * z = 10x
So here x is the starting value. It is successively multiplied by z
n = 4 times until we reach 10x.
So for
m = 0 result = x
m = 1 result = x * z
m = 2 result = x * z * z
m = 3 result = x * z * z * z
m = 4 result = x * z * z * z * z
So now all we need to know is the value of z.
From the first equation,
z^n = b
so
z = b ^ (1/n)
then:
result = x * z^m
examples
The tcsh script:
set m = 0
while ($m < 13)
# x (real): starting value
# b (integer): base of the scale (eg 2 or 10)
# n (integer): number of intervals
# m (integer): which interval we are on
# w (integer): width of output number (characters)
# d (integer): decimal places of output number (characters)
printf "%2d " $m
# x b n m w d
echo "1 2 4 $m 4 2" | logscale
@ m = $m + 1
end
gives:
0 1.00
1 1.19
2 1.41
3 1.68
4 2.00
5 2.38
6 2.83
7 3.36
8 4.00
9 4.76
10 5.66
11 6.73
12 8.00
output: messages to the user
description
Create numbers on a log scale one at a time for use in scripts.
Let the scale look like this (where b = 10):
x * z * z * z * z = 10x
So here x is the starting value. It is successively multiplied by z
n = 4 times until we reach 10x.
So for
m = 0 result = x
m = 1 result = x * z
m = 2 result = x * z * z
m = 3 result = x * z * z * z
m = 4 result = x * z * z * z * z
So now all we need to know is the value of z.
From the first equation,
z^n = b
so
z = b ^ (1/n)
then:
result = x * z^m
examples
echo "
documentation
documentation
see also
author
Thomas Dana Schneider
bugs
technical notes
*)
(* end module describe.logscale *)
{This manual page was created by makman 1.44}
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