**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:

z_{TOUGH2} = z + drift*time

where (drift*time) is the trend added to the calculated TOUGH2 output z_{TOUGH2}.
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.``>>> SET`

**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)
`

Page updated: July 29, 1997