AUTOCR Process
To access this process:
- Sample Analysis ribbon >> Geochemical Processes >> Auto Correlation Analysis.
- View the Find Command screen, select AUTOCR and click Run.
- Enter "AUTOCR" into the Command Line and press <ENTER>.
See this process in the Command Table.
Process Overview
Auto-correlation analysis is used to quantify and define anomalous thresholds and halo size on regularly grided soil sample lines. AUTOCR can also be used to measure dispersion limits in stream sediments, as long as fixed distances are used for sampling.
The process calculates the auto correlation function R-L of a single field against sample DISTANCE or LAG (see Figure 1). By default, lag distance is used to calculate the auto correlation function. If sample distance, or a multiple of sample distance is required, use the parameter SAMPDIST.
Anomalous samples related to lag or sample distance (LAG or DISTANCE) are identified by strong and well defined peaks of R-L, the covariance between neighboring samples. Dispersion limits from mineralized stream sediments are defined by breaks in slope along the stream sediment train as defined by LAG-L.
Note: There is a restriction of 4000 samples for a given line or dispersion train. For the analysis to be valid the data points must be equi-distant from each other. All fields containing the same value should be removed prior to the analysis. A plot macro should be written to display the results.
File Handling
The input file (&IN) must contain a sample identifier (*SAMPID) which is declared on input. There is an obligatory output file (&OUT) of the results containing the fields LAG-L, DISTANCE, R-L and the significance levels for each observation which can be viewed by the plotting processes, e.g. PLOTDA and PLOTAN.
Input Files
|
Name |
Description |
I/O Status |
Required |
Type |
|
IN |
Input file. Must contain sample identity field. |
Input |
Yes |
Undefined |
Output Files
|
Name |
I/O Status |
Required |
Type |
Description |
|
OUT |
Output |
Yes |
Undefined |
Output file includes LAG-L, DISTANCE. R-L the auto correlation function and SIGNIC the significance of the auto correlation function for use in graphical processes. |
Fields
|
Name |
Description |
Source |
Required |
Type |
Default |
|
SAMPID |
Compulsory sample identifier field. |
IN |
Yes |
Undefined |
Undefined |
|
F1 |
First variable for evaluation. If no variables are selected all variables will be processed. |
IN |
No |
Numeric |
Undefined |
|
F2 |
Second variable for evaluation. |
IN |
No |
Numeric |
Undefined |
|
F3 |
Third variable for evaluation. |
IN |
No |
Numeric |
Undefined |
|
F4 |
Fourth variable for evaluation. |
IN |
No |
Numeric |
Undefined |
|
F5 |
Fifth variable for evaluation. |
IN |
No |
Numeric |
Undefined |
|
F6 |
Six variable for evaluation. |
IN |
No |
Numeric |
Undefined |
|
F7 |
Seventh variable for evaluation. |
IN |
No |
Numeric |
Undefined |
|
F8 |
Eighth variable for evaluation. |
IN |
No |
Numeric |
Undefined |
|
F9 |
Ninth variable for evaluation. |
IN |
No |
Numeric |
Undefined |
|
F10 |
Tenth variable for evaluation. |
IN |
No |
Numeric |
Undefined |
Parameters
|
Name |
Description |
Required |
Default |
Range |
Values |
||||
|
SAMPDIST |
|
No |
0 |
Undefined |
Undefined |
||||
|
|
>0 Display results on the screen (0). |
No |
0 |
0,1 |
0,1 |
Example
!AUTOCR &IN(L10),&OUT(L10ACR),@SAMPID='ID',*F1(BA),*F2(SR),@SAMPDIST=20
Error and Warning Messages
|
Message |
Description |
|
*** Warning *** nnnnn Samples exceed the maximum of 4000. |
The first 4000 will be processed. |
|
*** Error *** No numeric fields on file (filename). >>> ERR 122 <<< ( fileno.) IN AUTOCR |
|
|
*** Error *** SAMPID field (fieldname) is not in input file. *** Error *** in reading data from file (filename). >>> ERR 200 <<< ( fileno.) IN AUTOCR |
|
|
*** Error *** Compulsory file, field or parameter missing. >>> ERR 120 <<< ( fileno.) IN AUTOCR |
|
