Parent Command
all third-level commands in block > PARAMETER

Subcommand
-

Description
This command specifies the expected variation sigma of a parameter p. sigma is used to scale the columns of the Jacobian matrix, yielding dimensionless and comparable sensitivity coefficients. While the solution of the inverse problem is not affected by the choice of the scaling factor, all the qualitative sensitivity measures are directly proportional to sigma:

scaled sensitivity coefficient:

If no standard deviation (see >>>> DEVIATION (p)) or parameter variation is specified, the scaling factor is taken to be 10 % of the respective parameter value. For sensitivity analyses, sigma can be taken as the perturbation one would apply to study the effect of the parameter on the modeling result.

Example
> PARAMETER
>> POROSITY
>>> MATERIAL: FAULT
>>>> expected VARIATION : 0.10
<<<<
<<<
>> ABSOLUTE permeability
>>> MATERIAL: FAULT
>>>> expected VARIATION : 1.00 (one order of magnitude)
<<<<
<<<
<<

> COMPUTATION
>> OPTION
>>> SENSITIVITY analysis
<<<
<<

See Also
>>>> DEVIATION (p)