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 an expression, but only its initial value is used.
See also: DELAY MATERIAL, DELAY INFORMATION
Restrictions: DELAY FIXED 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 Fixed Delay.
| Units: | DELAY FIXED ( unit , time, unit ) --> unit |
The input, initial value and output must all have the same units. The delay time must have the same units as TIME STEP.
Examples
DI = DELAY FIXED(I,22,I)
DM = DELAY FIXED( MAX( A, B ), C,A)
Invalid
D = A + DELAY FIXED( R, 3.2, 0.0 )
D = DELAY FIXED( B, T, B) + 1
DELAY FIXED must follow the equal sign, and it cannot be part of a more complex mathematical expression. These formulations can be made valid by defining an auxiliary variable to perform the indicated operations.
NOTES The minimum delay time is TIME STEP and shorter delay times will have the same effect as a delay time of TIME STEP. DELAY FIXED and the other DELAY functions are discrete event functions and do not change except at TIME STEP intervals regardless of the integration technique used.
Sample model: DELAY FIXED.mdl in FunctionExamples
