Table of Contents
potccd - Create an image with potentials or densities from a potential
potccd stores the potential
values of a potential descriptor (see potential(5NEMO)
) on a regular grid
in standard image(5NEMO)
format. It is also possible to store the Poissonian
density, either 2D or 3D. For this numerical derivatives of the force field
are used, and hence a small difference step needs to be given.
following parameters are recognized in any order if the keyword is also
ndim=2 the Z-coordinate is not ignored, and hence may give meaningless results
if forces depend on Z.
First a somewhat obscure way in to create
a map of an arbitrary function using the potname=rotcur lookup table. It
will use a spline interpolation, and if mode=pot is used, the "potential"
is actually the "rotation curve" itself, since in general one cannot easily
compute the potential from a rotation curve without knowing the full geometry.
Here is an example how to create a smooth radial profile of the function
"f(x)=1/sqrt(4+x)" on a grid from -10..10:
- Output file (image). No default.
- Name of the potential(5NEMO)
- Parameters for the potential.
- Any optional
data file associated with the potential.
- X-coordinate(s) to test potential
at. This should be a regular array, e.g. 1:10:0.2. Default: 0.
to test potential at. Default: 0.
- Z-coordinate(s) to test potential at.
- Time to test potential at
mode. Choices are potential, accelerations in X, Y or Z, and density (which
needs dr>0). Default: pot.
- Difference step used to compute numerical force
derivates that are used to compute Poissonian densities.
- Number of
dimensions used in Poissonian density computation. Should be 2 or 3.
% nemoinp 0:10 | tabmath - - '1/(sqrt(4+%1)' > map0.tab
% potccd map0 rotcur 0 map0.tab x=-10:10:0.1 y=-10:10:0.1
If the functional form is know, ccdmath(1NEMO)
will perhaps do better,
if not a little more involved to type.
10-Jun-92 V1.0 Created PJT
30-mar-94 V1.1 added density options (dr=, ndim=) PJT
12-sep-02 V1.2 added mode= PJT
Table of Contents