# Function

## Class Name

## Location in Objects Pane

## Properties

### Object Name

- Name of the object in Rt.
- Allowable characters include upper-case and lower-case letters, numbers, and underscore (“_”).
- The name is unique and case-sensitive.

### Expression

### Gradient Analysis Type

- Indicates the methods to compute the gradient of the limit-state function, including finite difference method and direct difference method.
- For more information, see Zhang-Der Kiureghian (1993) and Kleiber (1997)

### Perturbation Factor

- The forward finite difference estimate of gradient vector for each variable is equal to its standard deviation divided by Perturbation Factor which is typically set equal to 1000.

### Efficient Perturbation

- Efficient perturbation restricts Rtx to use perturbed values only for the models that are affected by variables' changes to recalculate function value. Two options are available: if the option “True” is set, program will run models affected by perturbation recognized by Rt, and in case the “False” option is set, the program will run all models for each perturbation.

## Read-only Properties

### Function Value

- The current value of function as the results of calculations

## Output

## Right-click Menu

### Remove

## References

- Zhang, Y., & Der Kiureghian, A. (1993). Dynamic response sensitivity of inelastic structures. Computer Methods in Applied Mechanics and Engineering, 108(1), 23–36
- Kleiber, M. (1997). Parameter sensitivity, J. Willey & Sons Ltd., Chichester