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DELAY MATERIAL (input, delay time, initial value, missval) discrete MATERIAL DELAY |
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The same as DELAY FIXED except that delay time can be a variable. If delay time is decreasing, some values of the input will be added to more recent inputs for output. If delay time is increasing, missval will be used when no output is available at a time. This function is particularly useful for modeling queues and production processes with varying and often random processing times.
Restrictions: DELAY MATERIAL must directly follow the equal sign. Vensim treats the variable on the left-hand side of the equation as a Level variable. In the Equation Editor choose type Level, subtype Material Delay.
| Units: | DELAY MATERIAL ( unit , time, unit, units ) --> unit |
The input, initial value, missing value and output must all have the same units. The delay time must have the same units as TIME STEP.
Examples
test starts = 1.0 ~~|
test time = RANDOM UNIFORM(4,6)~~|
test completions = DELAY MATERIAL(
test starts,test time,
test starts,0.0) ~~|
Availability: Not PLE or PLE Plus.
See also: DELAY FIXED, DELAY INFORMATION
Sample model: DELAY MATERIAL.mdl in FunctionExamples
