[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring
From: |
Rik |
Subject: |
[Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring |
Date: |
Tue, 19 Dec 2017 12:44:44 -0500 (EST) |
User-agent: |
Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:55.0) Gecko/20100101 Firefox/55.0 |
Follow-up Comment #7, bug #52685 (project octave):
@Dan: Could you write a note about the documentation philosophy on the
Maintainer's List? I think some of the changes are worth discussing first.
In the plaintext version of the help, for example, using @var() always
produces a CAPITAL, generally sans serif, font which can be confusing.
I think there is a distinction between saying what the code does, for example,
mean of a vector is
@example
@var{x} = 1 / length (@var{x} * sum (@var{x})
@end example
and the mathematical definition of the mean
@example
N
mean = 1 / N * sum (x_i)
i=1
where N is the number of elements
@end example
When defining a mathematical expression, y and x and other entries are general
variables, NOT the variables of this particular function, and therefore I
don't think they need the @var{} surrounding them.
In particular, once you go with @var{} you can't make the distinction between
vectors (lower case Roman alphabet) and matrices (upper case Roman alphabet).
For example,
y = M*x + b # definition
versus
@var{y} = address@hidden + b # what function computes
which renders as
Y = M*X + b
I don't have a function QUARTILE() in my distribution so I can't comment on
that. Maybe that is in the statistics package?
There does seem to be some confusion between in ols.m between whether SIGMA or
sigma^2 is being calculated. See Wikipedia
(https://en.wikipedia.org/wiki/Ordinary_least_squares). The correction in the
denominator is for the statistical degrees of freedom. The input x is a TxK
matrix. That means there are T rows (observations). If the matrix is square
and of full column rank then there is enough information to make the most
accurate determination of the parameters. If x is not square, and rank
deficient, then the estimate will not be as good. Still, for calculating the
variance the degrees of freedom, at the best of times, are N-1, which suggests
that there should be an extra 1 or 2 in this equation someplace. In
particular, I tried ols() and for a full rank set of measurements sigma is
returned as Inf because (T - rank (x) == 0). This isn't right.
You could also ask on the Maintainer's list about this for someone with
statistical expertise to weigh in on this.
_______________________________________________________
Reply to this item at:
<http://savannah.gnu.org/bugs/?52685>
_______________________________________________
Message sent via/by Savannah
http://savannah.gnu.org/
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring, anonymous, 2017/12/18
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring, Dan Sebald, 2017/12/18
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring, Rik, 2017/12/18
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring, Dan Sebald, 2017/12/18
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring, Dan Sebald, 2017/12/18
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring, anonymous, 2017/12/18
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring, Dan Sebald, 2017/12/19
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring,
Rik <=
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring, Dan Sebald, 2017/12/19
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring, Dan Sebald, 2017/12/19
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring, Rik, 2017/12/19
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring, Dan Sebald, 2017/12/19
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring, Rik, 2017/12/19
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring, Rik, 2017/12/19
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring, Dan Sebald, 2017/12/19
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring, Dan Sebald, 2017/12/19
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring, Rik, 2017/12/22
- [Octave-bug-tracker] [bug #52685] redundant sentence in meansq docstring, Dan Sebald, 2017/12/22