[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

*Subject*: Re: Convolution of Stick Spectra*From*: bjackel(at)phys.ucalgary.ca*Date*: Sat, 09 Sep 2000 18:44:53 -0600*Newsgroups*: comp.lang.idl-pvwave*Organization*: University of Calgary*References*: <tclement-0909001528490001@checont6.ucsd.edu>*Xref*: news.doit.wisc.edu comp.lang.idl-pvwave:21343

Hi Todd It helps a bit to pre-calculate your variance term. Cuts execution time from 27 to 18 seconds on my PC. variance_term= ( ( (.12*sqrt(energy/1000))/1.6651)*1000)^2 FOR indx=0L,nstick-1 DO BEGIN result = result + intensity[indx]* $ exp(-((energy_scale - energy[indx])^2)/ variance_term[indx] ) ENDFOR Nothing else springs to mind. Your energy dependent width is a real problem ie. can't use single FFT for convolution. If precision isn't a major issue, you could pre-calculate Gaussians for each energy bin (2048 of them) and just multiply by the appropriate intensities. Only useful if you'll be reading in lots of different spectra in each run. It'll be interesting to see what others come up with... Brian Jackel Todd Clements wrote: > > Hi all... > > In my on-going effort to speed up the code in our lab, I have another > 'challenge' for you (I have to put 'challenge' in quotes because it seems > that no matter what I ask, someone knows the ansewr off (or at least > nearly off) the top of their head!) > > We have a situation where we need to convolute (with energy dependent > gaussians) a number of stick spectra on a well-defined energy axis. The > stick spectra are read in from another program as a 2-dimensional array, > using ddread. The [0,*] elements are the energies of the sticks, and the > [1,*] values are the intensities. These have no inherent spacing, they are > just calculated intensities at whatever energy the calculation returns.

**Follow-Ups**:**Re: Convolution of Stick Spectra***From:*Todd Clements

**References**:**Convolution of Stick Spectra***From:*Todd Clements

- Prev by Date:
**Convolution of Stick Spectra** - Next by Date:
**Font problems in Linux** - Prev by thread:
**Convolution of Stick Spectra** - Next by thread:
**Re: Convolution of Stick Spectra** - Index(es):