README

In order to prevent disappointment and frustration this section should be carefully read and understood before you endeavor into NEMO.

You can use the list below as a checklist, it will help you to decide if NEMO is really the right way for you to solve your particular problem. In the end it may be helpful to have the manual pages programs(8NEMO) and/or index(1NEMO) for names of specific programs and utilities that you may want to use. The items in the list below are in approximate order of importance, the most important ones listed first. The further down the list you come, the easier it will be for you to get along with the NEMO package.

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understand NEMO is nothing more than an extension of the UNIX environment, and that you know how to modify your default UNIX environment to be able to run NEMO programs (See Appendix ). This generally makes it relatively easy to use NEMO in other environments and packages.

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understand the basic user interface: programs have a 'keyword=value' argument structure, and that there are 'program' and 'system' keywords. System keywords can generally be set fixed by an equivalent environment variable (Chapter , Appendix )

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realize NEMO is mainly an N-body package, with utilities to create stellar systems, evolving them, and a large variety of analysis and display programs. However, for a number of problems an N-body system can be effectively and efficiently used to simulate a completely different physical situation. There are interfaces to create/convert data in/to image format, and export them in FITS format (Chapter ). A small amount of orbit and table manipulation utilities are also available. (See also Chapter ).

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understand the basic workings of a UNIX shell; how to write shell scripts in which programs are combined in a modular way, and to automate procedures. For this reason NEMO programs are also geared towards batch usage. (see any introductory UNIX book and Appendix )

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understand that data is stored in binary format and in a general hierarchical/ structured file format. The data can always be viewed in human readable form with the program tsf(1NEMO). Depending on the kind of data, the format is structured in a specific way, e.g. snapshots, images, orbits. Only problem specific programs can read such datafiles (See Chapter ).

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you know about the graphics interface yapp (see also Chapter ). Make sure you understand the local NEMO implementation how to get graphics output to for example screen and printer. Sometimes they are hidden in one device driver, and the yapp= system keyword is then used to select the device (e.g. the mongo and pgplot yapp drivers), or programs are linked with different device drivers. In this case, the program name will have a underscore and the device name appended, such as snapplot, snapplot_cg and snapplot_ps. (See Chapter ).

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realize that NEMO can be extended to suit your own needs. It is fairly easy to write new programs or even define a new data structure (as was done for snapshots, images and orbits). Do realize however that the main language used is C and support for linking FORTRAN and C is minimal and system dependant. (See Chapter ).

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you realize what it means to install NEMO if this has not been done yet. You need to carefully read Appendix  in detail; any experience you have had with the UNIX shell, and utilities like ``make'' and ``autoconf'' will be useful.