Manual Page for Command >> DRIFT


Syntax
>> DRIFT

Parent Command
> PARAMETER

Subcommand
>>> NONE
>>> SET

Description
This command selects as a parameter the slope of a time-dependent trend. The trend is added to the TOUGH2 output referring to a specific data set:

zTOUGH2 = z + drift*time

where (drift*time) is the trend added to the calculated TOUGH2 output zTOUGH2. The result z is compared to the measurement z* of the corresponding data set. This option allows removal of a trend in the data (for example, a flowmeter may exhibit an unknown offset and time-dependent trend that needs to be estimated). A non-zero value must be provided as initial guess through the iTOUGH2 input file using command >>>> GUESS. The data set is identified by number using command >>> SET (p).

Example
> PARAMETER
estimate coefficients of regression dz=A+B*time to correct flowmeter data
>> SHIFT
>>> NONE
>>>> ANNOTATION: coefficient A (constant)
>>>> INDEX : 2 3 4 (identifies data sets)
>>>> GUESS : 4.0E-6 [kg/sec]
<<<<
<<<
>> DRIFT
>>> NONE
>>>> ANNOTATION: coefficient B (slope)
>>>> INDEX : 2 3 4
>>>> GUESS : 1.0E-9 [kg/sec/sec]
<<<<
<<<
<<

See Also
>> FACTOR | >> LAG | >> SHIFT | >>> SET (p)


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Page updated: July 29, 1997