Page 721 - ExtendSim User Guide
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Generates random numbers for the distribution selected in the dialog. Select from over 30 distributions or use an empirical table to create a custom distribution. This block is discussed more in “Random numbers” on page 703.
Data Fitter (Utilities library)
Uses matrix techniques to obtain a least mean square curve fit to a set of data. Enter or import the data into the dialog’s data table and select a fitting function to solve for.
☞ In addition to the blocks listed above, most blocks automatically calculate and report statistical information during or at the end of a simulation run. For example, the Math block (Value library) reports the results of the selected mathematical calculation in its Options tab and the Queue block (Item library) displays statistics about the queue length, average wait time, utili- zation and so forth in its Results tab.
Other options
There may not be an ExtendSim block that provides the specific function or equation that you want. Or, you may want to combine the functionality of several blocks into one. Some possible solutions are:
• Select several blocks and make them into a hierarchical block, as discussed in “Hierarchy” on page 618.
• Add features to an ExtendSim block by modifying the structure of a block (its dialog and code) as discussed in the ExtendSim Developer Reference.
• UsetheEquationblock(Valuelibrary)ortheEquation(I)orQueueEquationblocks(Item library) to directly combine functions or to obtain behavior not available in other blocks. These blocks are discussed in the next topic.
Equation-based blocks
The equation-based blocks calculate values for models based on formulas and ModL code entered in their dialogs. There are five mathematical equation-based blocks:
Math and Statistical Distributions 695
Equation-based blocks
Random Number (Value library)
Block Equation
Equation(I) Queue Equation
Query Equation Query Equation(I)
Library Value
Item Item
Value (AT & Suite) Item (AT & Suite)
Purpose
Computes user-defined equations and outputs the results
Computes user-defined equations when an item arrives, then outputs the results
Stores items and releases them based on the results of user-entered equations. See “Sorting items using the Queue Equation block” on page 145.
A user-defined equation selects one record from an ExtendSim database table
A user-defined equation selects one record from an ExtendSim database table when an item arrives
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