# delayMaterial

delayMaterial is
the system dynamics function
that returns the value of the input delayed by the delay time.

The
initial value is the value
of the variable on the left-hand side of the equation at the start of
the simulation. The 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, missingValue 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.

#### Example:

delayMaterial can
be called
in formulas of system dynamics variables.

delayMaterial function
has the following notation:

- delayMaterial(flow, delayTime, initialValue,
missingValue)

flow can
be a flow variable, or a numeric expression of any complexity.

delayTime can
be either a
constant or a numeric
expression (e.g. a function call, or a numeric parameter).

initialValue - initial value.

missingValue - this value is used when delay time is increasing and no output is
available at a time.

#### Units:

flow
-> unit

delayTime -> time

initialValue ->
units

missingValue ->
units

delayMaterial()
-> unit

#### Related topics

delay

delay3

smooth

smooth3

delayInformation