INTRODUCTION

When GiD is to be used for a particular type of analysis, it is necessary to predefine all the information required from the user and to define the way the final information is given to the solver module. To do so, some files are used to describe conditions, materials, general data, units systems, symbols and the format of the input file for the solver. We give the name Problem Type to this collection of files used to configure GiD for a particular type of analysis.
Note: You can also learn how to configure GiD for a particular type of analysis by following the Problem Type Tutorial; this tutorial is included with the GiD package you have bought. You can also download it from the GiD support web page (http://www.gidhome.com/support).
GiD has been designed to be a general-purpose Pre- and Postprocessor; consequently, the configurations for different analyses must be performed according to the particular specifications of each solver. It is therefore necessary to create specific data input files for every solver. However, GiD lets you perform this configuration process inside the program itself, without any change in the solver, and without having to program any independent utility.

To configure these files means defining the data that must be input by the user, as well as the materials to be implemented and other geometrical and time-dependent conditions. It is also possible to add symbols or drawings to represent the defined conditions. GiD offers the opportunity to work with units when defining the properties of the data mentioned above, but there must be a configuration file where the definition of the units systems can be found. It is also necessary to define the way in which this data is to be written inside the file that will be the input file read by the corresponding solver.
From the 13th version of GiD, a new system of problemtye has been implemented (based in the CustomLIB library). Although the 'classic' problem type system is still supported by GiD, it is considered deprecated, as the new one offers clear advanteges in terms of usability, performance and integration cappabilities. Documentation about the deprecated classic problem type system can be found in the annex of this manual APPENDIX B (classic problemtype system).
This new problem type definition uses a single .spd file to describe general properties, materials, conditions and units (as a tree with xml syntax). All this data is showed in a 'tree view', and materials and conditions are associated to groups of enties.
About writting the input file, Tcl commands are used to write the data in files (optionally aided with the special funcion GiD_WriteCalculationFile for efficiency).
The new problem type creation system lean on a collection of tools, which facilitates the development of advanced problem types for customizing the personal pre and post processor system GiD for computer simulation codes. It is based on a XML hierarchical structure and an automatic physical tree view.