8. OUTPUT FILES

SAVE YOUR OUTPUT!

When Michlet is run, one of the first things it does is to clear its output files by placing the character string # Blank in each file. If you have not copied the files to a safe directory before running Michlet, previous output will be over-written. I have found it very useful to create some small batch files (or scripts in Unix) that copy data to safe directories or to floppy or compact disk.

out.mlt

This comma-separated text file is created when you exit from Michlet. The file contains, among other output quantities, details of the hullforms, tables of resistance, and an array of (dimensionalised) hull offsets. If drag was not calculated before exiting Michlet, all resistances in this file will be equal to zero.

Certain quantities are not calculated in this version. If the words 'Not calculated' or 'Not' appear next to a label in the output file, it means that the calculation of that quantity is crippled in the current version.

More Output Files

Some users like the fact that nearly all output data is contained in the one file, namely out.mlt; others prefer to make up their own data sets using small files that contain specific information, such as particular components of resistance. The following files contain information that is in out.mlt but in a format more suitable for processing by Unix utilities, DOS batch files etc. All files listed below will be cleared when Michlet is run. You should save any output immediately after Michlet terminates.

Wave Elevation and Resistance Output Files

Resistance graphs, wave elevation contour plots and free wave spectrum graphs can be saved as .pcx files. Wave elevations and free wave spectra can also be saved as text (.mlt) files. Press s to save the data for wave elevations. A prompt will appear asking for a filename (maximum 8 letters). The extension .mlt will be appended automatically. Press S to save a resistance, wave elevation or free wave spectrum plot as a .pcx file. The .pcx extension will be added automatically.

It is very important to note that wave elevation data is not saved automatically on exit. After you display wave patterns or wave cuts you should save the data, or the graphic, or both.

The table below is an example output file of wave elevations for a small rectangular patch using a 5x5 grid. Of course, for real work, the size of the output file will be much larger. Also, the elevations will not always be symmetric around y=0.0 for all ships and all rectangular patches. Output is comma-separated, and can be pasted into Excel spreadsheets.

RECTANGULAR PATCH
Speed
6.0000
x0,x1,nX
20.0000,40.0000,5
y0,y1,nY
-10.0000,10.0000,5
x_zmin,y_zmin,zmin
40.0000,-5.0000,-0.0227
x_zmax,y_zmax,zmax
20.0000,-5.0000,0.0139
ELEVATIONS
z,20.0000,25.0000,30.0000,35.0000,40.0000,
10.0000,0.0011,-0.0002,-0.0012,0.0033,-0.0032
5.0000,0.0139,-0.0166,-0.0002,0.0095,-0.0227
0.0000,0.0028,-0.0033,0.0015,0.0001,0.0011
-5.0000,0.0139,-0.0166,-0.0002,0.0095,-0.0227
-10.0000,0.0011,-0.0001,-0.0012, 0.0033,-0.0032

Speed is in metres/sec. x0,x1,y0, and y1 are the ordinates (in metres) of the corners of the patch. nX and nY are the number of grid nodes in the X- and Y-directions.

x_zmin and y_zmin are the co-ordinates (in metres) of the minimum wave elevation in the rectangular patch. zmin is the minimum wave elevation. x_zmax and y_zmax are the co-ordinates (in metres) of the maximum wave elevation in the rectangular patch. zmax is the maximum wave elevation.

Wave elevations, z, are given as a table of values. The first row contains the x-ordinates of the grid points of the rectangular patch; the first column contains the y-ordinates for the patch.

This file can be used as an input file for the ship-identification objective in GODZILLA by renaming it as userrecp.mlt. No other changes to the file are necessary, making it easy to use with DOS batch files or Unix scripts.

Output files for the sectorial patch and the wave cuts have a very similar format to the above table.

Output Formats

The variety, type, and format of output files is controlled by the values of the two input variables Output File Type and Output File Subtype in the in.mlt input file. For example, in addition to the files described above, Michlet can output files that make it easy to create lines drawings using public domain programs like gnuplot, or to automatically generate text and tables using LaTeX. Description of the many different possibilities is beyond the scope of this manual.


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