![[attach.png]](../idldoc-resources/attach.png)
math/
point_convolve.pro
top source point_convolve
Math
result = point_convolve(points=points, binsize=binsize, range=range, sigma=sigma, weight=weight, cutoff=cutoff, noconvol=noconvol, nofft=nofft)
Convolves a list of N-dimensional points with a Gaussian kernel.
By default, this function uses an FFT and the convolution theorem. If /NOFFT is set, then it uses the built-in CONVOL function. If either /NOCONVOL is set or SIGMA is an MxN array, then it uses manual summation.
Return value
An grid containing the output density field. Each dimension i in the output grid has length (RANGE[i,1]-RANGE[i,0])/BINSIZE[i]. Returns -1 on error.
Keywords
- points in
Array of MxN points for M dimensions and N particles (required).
- binsize in
Bin sizes for final output grid. Either a scalar or an array of length M. (required)
- range in
Array of Mx2, containning the extent of output grid in each dimension. (required)
- sigma in
Width of Gaussian kernel. May either be a scalar that is applied to all dimensions, an array of length M for different widths in each dimension, OR an MxN array containing a separate width for each particle and dimension (this option uses manual summation as if /NOCONVOL were set, and is therefore much slower). (required)
- weight in
An array of length N containing the weight to assign to each point. A weight of 1 (default) corresponds to a Gaussian normalized such that its integral over the entire M-dimensional space is unity.
- cutoff in
Assume that the kernel may be safely truncated after this many SIGMAs. Default: 8 (corresponding to a dynmical range of 7.9e13).
- noconvol in
If /NOCONVOL is set than use manual summation rather than an FFT.
- nofft in
If /NOFFT is set then use the built-in CONVOL routine rather than an FFT.
Examples
xpos = 10.*RANDOMU(seed,100)
ypos = 20.*RANDOMU(seed,100)
density = POINT_CONVOLVE(POINTS=TRANSPOSE([[xpos],[ypos]]),
BINSIZE=1., RANGE=[[0.,0.], [10.,20.]], SIGMA=[2.,4.])
Author information
- History:
Written by: Jeremy Bailin 12 June 2008 Public release in JBIU 15 Apr 2008 Fixed off-by-one bug and improved memory usage
File attributes
| Modification date: | Mon Feb 15 12:18:03 2010 |
| Lines: | 298 |