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Name

rotcurshape - format for rotation curve shapes

Synopsis


#include <nemo.h>
real rotcur_NAME(real r, int n, real *p, real *d);
DescriptionA rotcurshape file is a small C function that should return
the value of the rotation curve at a given radius. This function will be
loaded  (from the corresponding .so file) by NEMO’s dynamic object loader
(see also loadobj(3NEMO)). The rotation curve is parameterized by n parameters
p[0]...p[n-1]. The function should also return the ’n’ partial derivatives d[i]
= dV/dp[i], for i=0...n-1 
The name of the function should be rotcur_NAME()
where NAME is the rotcurshape name . 
ExamplesThe following example is a
rotation curve of a simple linear core: 
#include <nemo.h>
real rotcur_core1(real r, int n, real *p, real *d)
{
  real x = r / p[1];
  d[0] = x/(1+x);
  d[1] = -p[0]*d[0]/(p[1]*(1+x));
  return p[0] * d[0];
}
Assuming this is in a file core1.c, the command
    bake core1.so
will create a shared object file, which can then be used by rotcurshape:
  % rotcurshape in=... radii=...  rotcur1=core1,100,2,1,0
would fit a linear core with fixed core radius of 2, and initial guess of V=100 and will fit the velocity scaling V.

Although there are examples in $NEMO/src/image/rotcur/shape, most shapes are builtin to the program rotcurshape(1NEMO) .

See Also

rotcurshape(1NEMO)

Author

Peter Teuben

Files


~/src/image/rotcur/shape    examples

Update History


25-jan-08    documented    PJT


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