FFUNC Process

To access this process:

Enter "FFUNC" into the Command Line and press <ENTER>.
Display the Find Command screen, locate FFUNC and click Run.

See this process in the Command Table.

Process Overview

The F function estimates the variance of a point in a block, based on a variogram model which is selected from the input variogram model file VMODPARM.

The block whose F value is to be calculated is simulated by a 3 dimensional matrix of discretisation points. The F value is calculated as the average value of the variogram between each possible pair of discretisation points.

The number of discretisation points in each of the X, Y and Z directions is specified by parameters IPOINTS, JPOINTS and KPOINTS. It is recommended that a minimum of 4 x 4 x 4 points is used. The processing speed is proportional to the number of points used.

You will be prompted interactively to enter the X, Y and Z dimensions of the block. The F value will be displayed in the Output window, and you may then enter the dimensions of another block, or ! to terminate the process.

By estimating the F-function for two block sizes, the theoretical Dispersion Variance for selective mining units within a kriged block can be calculated. This can then be used as input to processes SMUHIS and SMUMOD.

Note: You will be prompted interactively to enter the dimensions of the block whose F value is required.

Input Files

Name	Description	I/O Status	Required	Type
VMODPARM	Input variogram model file.	Input	Yes	Variogram - Model

Output Files

Name	I/O Status	Required	Type	Description
OUT	Output	No	Undefined	Optional output file. This will contain the block dimensions and F value in fields XINC, YINC, ZINC and FVALUE.

Parameters

Name	Description	Required	Default	Range	Values
VMODNUM	Variogram model number, as defined by VREFNUM field in VMODPARM file. Default (1).	No	1	Undefined	Undefined
LOG	Log/Normal variogram flag. Default(0). The variogram model, as defined by VGRAM , is Normal if LOG =0 or Lognormal if LOG =1.	No	0	0,1	0,1
IPOINTS	Number of discretisation points in X dimension to simulate block (6)	No	6	Undefined	Undefined
JPOINTS	Number of discretisation points in Y dimension to simulate block (6)	No	6	Undefined	Undefined
KPOINTS	Number of discretisation points in Z dimension to simulate block (6)	No	6	Undefined	Undefined

Example

!FFUNC &VMODPARM(vmodel), &OUT(fvalues), @VMODNUM=1, @LOG=0,

@IPOINTS=6, @JPOINTS=6, @KPOINTS=6

Calculation of Average Value of Variogram within 3D Block
---------------------------------------------------------
Variogram model file VMODEL includes fields for up to 9 structures.
The file contains 10 records.

Model 1.00 has been retrieved from file.
Number of fully defined structures = 2
N Nugget Variance = 1.6000
G1 Rotation Angle 1 = 22.5  X1 Rotation Axis 1 = 3 (Z)
G2 Rotation Angle 2 = 0.0   X2 Rotation Axis 2 = 2 (Y)
G3 Rotation Angle 3 = 180.0 X3 Rotation Axis 3 = 1 (X)
Structure Model Type Range X Range Y Range Z Spatial Var
               T          AX      AY      AZ        C
    1          1        19.0    23.0    43.0   2.9000
    2          1        38.0    64.0    90.0   2.3000
    3          1           -       -       -        -
Number of discretisation points in X,Y,Z =   6   6   6

You will now be prompted to enter the X,Y and Z dimensions of the 3D block.

Enter the next block size (or ! to terminate):
----------------------------------------------
X Block Size >10
Y Block Size >12
Z Block Size >5

F-function estimate for block of size 10.000 x 12.000 x 5.000
Average value of variogram in block = 3.1309

Enter the next block size (or ! to terminate):
----------------------------------------------
X Block Size >!