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# Calculation

## Calculation Start

To start the optimization, open the Optimization Settings dialog box. Make sure the Active check box is selected in the "Optimization" section. Then, click the button to close the dialog box.

## Optimization Process

The "Calculation Progress" window appears, where you can follow the optimization process. The "Current Calculation" section shows the currently analyzed model variant ("mutation") and the total number of mutations.

Once the analysis starts, the program determines all or an initial selection of parameter constellations, depending on the selected optimization algorithm. The starting values are determined with a random generator. This is done using a method similar to the Monte Carlo method, as described here Wikipedia article.

As a result, a loop process runs until it reaches the total number of all mutations to be analyzed. The following steps are carried out:

• The determined parameter constellation is used in the global optimization parameters.
• All defined analyses and design checks are carried out, as in the case of the "Calculate All" function.
• The results obtained from this are interpreted with regard to the defined optimization criterion.
• The result of the analyzed variant is compared with the other results in the "Optimization" table and sorted there, depending on the result.
• A new parameter constellation is determined on the basis of the completed analysis.
Tip

In the work window, you can follow the changes to the model graphic during the optimization in real time. They result from the constantly reassigned parameter constellations. In the table, the best parameter constellations so far are given in the upper rows.

## Increasing Efficiency

The duration of the entire optimization process depends primarily on the number of model variants to be processed ("mutations") and the analysis effort for a single model mutant. The latter includes all analyses assigned to the model (load cases, load combinations, design situations), including all design add-ons that contain the design specifications. In order to ensure that the process does not determine irrelevant results for the interpretation in the following parameter constellations, the analysis of the mutant is immediately aborted and the next mutant is switched on in the case of instabilities (in the structural analysis) or non-designable situations (in the design). Aborted variants also do not appear in the "Optimization" table.

Which parameter constellation is selected during the optimization process, depends on two factors: On one hand, the optimization algorithm ("Optimizer") specifies the solution method; on the other hand, the definition type of the optimization parameters specifies the direction in which a parameter constellation is analyzed (see the image Defining Global Parameters for Optimization ). The optimization parameters of the "Optimization" type are neutral for the optimization process and do not have a specific direction to be used in order to reach the optimization criterion in the best possible way. The parameters of the "Optimization | Ascending" type or the "Optimization | Descending" type have a directional effect on the optimization process. The "Ascending" or "Descending" attribute suggests the process of selecting the next parameter constellation in which direction the parameter should be changed in order to reach the optimization goal in the best possible way. Thus, you can control and accelerate the optimization process.

Parent Chapter

#### Technical Article

Optimizing Parameters in RFEM 6/RSTAB 9