FORECAST(input, average time, horizon)        A trend extrapolating FORECAST

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Returns a forecast of the value the input will take on at Time + Horizon.  Equivalent to the equations:

FORECAST=input*(1+TRD*horizon)

TRD = ZIDZ(input-AV,average time*AV)

AV=INTEG((input-AV)/average time,ininput)

The FORECAST function provides a very simple trend extrapolation forecast of the future value of a variable based on its past behavior.  Like any trend extrapolator it performs very badly at turnarounds.

 

Units: FORECAST(units,time,time) --> units

The input units match the output units.  Units for the average time and the horizon must match those of TIME  STEP.

Example

R = 10 + RAMP(1,10,60)

RD = DELAY FIXED(R,10,R)

FR = FORECAST(RD,5,10) 

See also: TREND, SMOOTH

Sample model: FORECAST.mdl in FunctionExamples