--- Welcome to the Atmlab package of Matlab functions ---
Copyright (C) 2002-2010
Patrick Eriksson
Oliver Lemke
Christian Maetzler
Stefan Buehler
Bengt Rydberg
and many others
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option) any
later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
USA.
For further information
-----------------------
AUTHORS: The people who has contributed to Atmlab.
CONFIGURE: How to set-up Atmlab for your personal use.
INSTRUCTIONS: Instructions for Atmlab developers.
When Atmlab is added to the Matlab search path (as described in CONFIGURE)
you get a small introduction by:
>> atmlab_demo
Guidelines for atmlab functions
-------------------------------
There are no totally strict principles for atmlab functions, but the
ambition is to follow the guidelines below. Exceptions exist, for
example, imported function sets are not revised to match the
guidelines (importing updates would then be quite demanding).
The functions shall not require access to special toolboxes.
The functions shall have a clear header. Mandatory and optional
variables shall be cleared identified in the header, with allowed
choices for the input also clearly described. If nothing else is
stated, setting an optional input argument to [] signifies to use the
default value.
A distinction is made between numerical and logical 0 and 1. To obtain
a logical variables, use logical expressions or the functions false,
true or logical. The terms "flag" or "boolean" (used in atmlab
function headers) signify a single logical value. The function
*isboolean* identifies if a varaible matches this definition.
Matlab is classifying also non-numeric data as scalars and vectors.
In addition, all data are considered to have a dimension of at least
two and there is no clear definition of a vector in Matlab. In Atmlab,
the terms scalar, vector, matrix and tensor are used only for numeric
data. A scalar treated to have dimension zero. One dimensional data
shall be given (and returned) as column vectors (exceptions can be
accepted where the size does not matter). The function *dimens* can be
used to determine the effective dimension of data according to
atmlab's definition of scalars and vectors. Two dimensional data are
denoted as a matrix. A tensor is a data container of any
dimension. For example, vectors are one dimensional tensors.
This means that the Matlab functions *isscalar* and *isvector* should
not be used inside Atmlab. Other Matlab is-functions are used and
followed. For example, cell array of strings (see *cellstr* for a
definition) are used frequently and correct type is here checked by
*iscellstr*. To avoid confusion with e.g. *isvector*, Atmlab uses here
the notation of tensors throughout in function names (that can be
reflected in some error messages and function headers). Accordingly,
Atmlab includes functions such as *istensor0* and *istensor1*.
The general rule is that numeric data shall either be scalars or all
have the same size. This to allow that expressions can use .* and ./
without any modification of the input. Accordingly, the data are
scalar fields (and not grids). A scalar corresponds to a constant
field. For example, to calculate the total number density for all
combinations of some vectors with pressures and temperatures
vmr2nd(1,repmat(p,1,length(t)),repmat(t',length(p),1))
The above gives a matrix while
vmr2nd(1,p,t)
gives a vector.
For cases where this general rule can be applied, the sizes are not
commented in the function header and the sizes are not checked
specifically by the function. If the data sizes do not match, there
will be a general error of the type "Matrix dimensions must
agree.". However, there are many cases where all the input does not go
into a single equation and the function header shall then comment on
size requirements of the data and there should be clear error messages.
The comment %&% marks lines that can be removed for 'operational
applications'. That is, calculations where the code has been carefully
tested and data checks are skipped to obtain a higher calculation
speed. The code is stripped from lines including %&% and pure comment
lines by the script ???? (to be implemented).
It is recommended to join the atmlab-dev mailing-list, see
https://www.sat.ltu.se/mailman/listinfo/atmlab-dev