Elegant users forum

Hi,

I am trying to use 'sddsemitproc' but running into various problems. All the examples that I have seen - in this forum or in the documentation - assume that elegant has generated the data. Suppose I have data in spreadsheet and want to analyze it. If I understand the documentation correctly, I generate an sdds file of the data (R11, R12, R33, R34, Sx, Sy) and I'm good to go.

When I try something like: sddsemitproc ScanData.sdds OutData.sdds

I get the following error: 'Error: number of error sets must be >2'. I thought specifying errors was optional. Any help would be appreciated!

--chris

P.S. I am attaching an input file, which is itself curious because according to 'sddscheck' the file is corrupted. However, I can still plot columns with 'sddsplot' (?!).

Chris,

sddsemitproc requires that you perform error analysis. It allows the logic of the program to be significantly simplified. If you aren't interested in errors, then use a command like
% sddsemitproc ScanData.sdds emit.sdds -nErrorSets=3 -errorLevel=1e-9,1e-9

Also, your file has two problems:
1. You don't have a row counts value before the table, nor do you have no_row_counts=1 in the data statement.
2. You need to add a column called Step to the file. sddsemitproc requires this as an independent variable. You can add this as follows:
% sddsprocess ScanData.sdds -define=col,Step,i_row,type=double

--Michael

Hi Michael,

I was wondering if you could briefly explain the method used to extract emittances in sddsemitproc. I have been analyzing some data (simple, single quad scan) and comparing with the results of a multiple regression fit of the data. I get good agreement. But when I remove some data points, it seems that sddsemitproc is more sensitive to those changes than a simple regression fit. I was just curious about the method you use.

Thanks,
chris

Chris,

The method is described in my Ph. D. Thesis (SLAC R-402). The relevant pages are attached.

--Michael