Can LS-OPT handle discrete variables?

LS-OPT can handle discrete variables and even discrete variables in combination with continuous variables, as well as discrete variables with string values.

Discrete Variables

To define a discrete variable in LS-OPT, the user has to specify a name, a starting value and a list of allowable values.

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Mixed-discrete optimization

Discrete variables can be used together with continuous variables. This is called mixed-discrete optimization. The steps to compute a mixed-discrete optimum are

Consider all the discrete variables to be continuous and optimize. This continuous optimum found is used as the starting design in the next phase.
Discrete optimization is done considering only the discrete variables with the continuous variables frozen at the values found in the previous phase.
Continuous optimization is done considering only the continuous variables and with the discrete variables frozen at the values found in the previous phase.

Example: Discrete optimization

Sampling at discrete points

A flag is provides to select the sampling points at specified discrete values of the variables if discrete variables are specified. Discrete sampling will also handle discrete-continuous problems correctly. In the GUI, a switch box is provided for each discrete variable in the variables panel to define discrete sampling.

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If possible, a continuous sampling is recommended, because it usually leads to a better distribution of the points within the design space and hence to a better metamodel quality.

String Variables

As a special type of discrete variables, string variables may be defined in LS-OPT.

To define a string variable in LS-OPT, the user has to specify a name, a starting variable and a list of allowable values.

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