Manual Page for Command >>>> LOGARITHM

Syntax
>>>> LOGARITHM

Parent Command
all third-level commands in block > PARAMETER

Subcommand
-

Description
The parameter p to be estimated is the logarithm of the TOUGH2 parameter X:

p=log10(X) <=> X=10p

Estimation of logarithms is recommended if the parameter is expected to vary over a large range of values, suggesting a log-normal distribution of its estimate. Note that all quantities referring to this parameter are also in log-space (e.g. range, standard deviation, step length, etc.). Estimating the logarithm is chosen here over estimating the parameter value directly (command >>>> VALUE), estimating a multiplication factor (command >>>> FACTOR (p)), or estimating a log-normally distributed multiplication factor (command >>>> LOG(F)).

Example
> PARAMETER
>> ABSOLUTE permeability
>>> MATERIAL: SAND1
>>>> estimate LOGARITHM (this is the default for this parameter)
>>>> initial GUESS : -12.0 = 1 darcy
>>>> admissible RANGE : -15.0 -9.0
>>>> standard DEVIATION : 1.0 order of magnitude
>>>> maximum STEP size : 0.5 log-cycles per iteration
<<<<
<<<
<<

See Also
>>>> FACTOR (p) | >>>> VALUE

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Page updated: July 29, 1997