Usage of Lvmview

March 16, 2005

 

The Matlab function Lvmview has been developed to view ASCII files containing measurement data. If times are recorded, the recommended format is decimal. The ":"-format may differ from the Matlab time format (e.g. Dasylab files have a different time format).

Specifications to be fulfilled by the ASCII files are given in Help, General, or in the document Usage.doc. Some incidental occuring error message are discussed at the end of this manual.

The data can be viewed directly in the program Lvmview. After closing Lvmview, the data are kept in the workspace, and commands as mean(A) and plot(A(:,2)) can be given.

 

The use of Lvmview will be explained here.

 

1.       Start Matlab.

 

2.       Go to folder D:\Matlab_progs\Labprogs.

 

3.       Type: Lvmview.

 

4.       In the menu bar, click on File, followed by  Open.

 

5.       The box Input File is shown; find the file to be viewed, and select it.

 

6.       The box Read all data? will be shown. In most cases, yes is the best choice. Choose no in case of a file of 10 MB or more only.

 

7.       The number of header lines will be asked. Specify 0 if the input file has been created by Dasylab, because the program detects the end of the header of Dasylab files.

If no is specified in pint 6, begin sample, end sample, and step size are asked as well. Lvmview will send a warning if there are too many data to be read in once.

 

8.       The parameter screen appears. Fill in the values asked by the screen:

·         time step in the data file (this is not read from the header, because all types of ASCII files can be read),

·         number of the column where the time has been stored (0 if no times are written to the data file, or if ":" is present in the time format).

 

9.       The window channels appears. Select the channels to be plotted by clicking the mouse and holding the <control> key.

 

10.   A plot of all samples of the first and the last channel will be shown, combined with a dialog box asking the time interval to be plotted on the screen. The times can be read from the horizontal axes. Fill in the desired interval, and click on OK. The samples chosen are displayed on the next screen. Close the figure to continue.

 

11.   Click on Plot on the menu bar. Choose one of the next possibilities:

·         plot channels separated in subplots, 3 channels per figure,

·         plot all channels in one figure,

·         choose other samples,

·         choose other channels.

 

12.   If one of the plot options has been chosen, one or more figures appear. The figures can be edited (see the manual "Using Matlab Graphics"), and/or printed. If wanted, the figure can be saved by clicking File, save as on the menu bar of the figure, and afterwards the figure can be opened by clicking File, Open on the menu bar of Lvmview.

If another time interval must be viewed, close the figures and press Plot, option samples on the menu bar.

 

13.   After closing the figures, File, Open can be used to open a new file. This can be a figure (.fig), or an ASCII file. A .fig file always will be opened as a picture, and all other files will be opened as a data file. The old file will be kept in the workspace as long as no new file has been read, even after closing Lvmview. At the next restart of Lvmview, the file last read can be plotted again without reopening it.

 

To close Lvmview, always click the upper right cross, or click on File, Exit. Before closing Lvmview, check if all figures are closed (the figures are not closed automatically).

 

 

The next errors may occur:

 

 

Number of colums in line -- of ASCII file ... must be the same as the previous line.

 

In such a case, remove all spaces, signs, or numbers from the first position of each header line.

 

If the number of header lines specified is more than the actual number, no message will occur, but less data lines will be read.

 

 

where nchan is the number of channels used. If more data are needed, change the value of maxnum in \Functions\FN_indata7, line 86, or read the file in parts, using different sample numbers. Sample numbers to be read can be specified via the dialog box:

 

   read all samples?

           

            Specify No in this case.