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Process Help POLREG - calculate polynomial regression coefficients |
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Process Name |
Menu Path |
Link to Command Table |
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POLREG |
Introduction
Polynomial regression. The polynomial fitted is up to the 5th order, and thus includes a regression line.
How to use
The polynomial is of the form:-
Y = C0 + C1*X + C2*X2 + C3*X3 + C4*X4 + C5*X5
where the coefficients C0, C1, C2, C3, C4 and C5 are written to the output file.
The input file must contain two explicit numeric fields *X and *Y. The polynomial is calculated as Y estimates for X values. There must be at least (order+1) points. If either the *X or *Y value is absent data in a particular record, the record is ignored. This allows regression polynomials to be computed on incomplete sets of data; for example original assays and a partial set of check assays.
DATAFILE: Name of the input data file.
XDATA: The X field in the input file that was used.
YDATA: The Y field in the input data file that was used.
GOODNFIT: The goodness of fit.
CORRCOEF: The coefficient of variance.
STDERR: The standard error.
Files, Fields and Parameters
Input Files
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Name |
Description |
I/O Status |
Required |
Type |
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IN |
Input file. |
Input |
Yes |
Undefined |
Output Files
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Name |
I/O Status |
Required |
Type |
Description |
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OUT |
Output |
No |
Undefined |
Output file containing the coefficients. |
Fields
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Name |
Description |
Source |
Required |
Type |
Default |
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X |
X co-ordinate of the sample data. |
IN |
Yes |
Numeric |
X |
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Y |
Y co-ordinate of the sample data. |
IN |
Yes |
Numeric |
Y |
Parameters
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Name |
Description |
Required |
Default |
Range |
Values |
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ORDER |
Order of the polynomial required (1,2,3,4 or 5). |
Yes |
1 |
1,5 |
1,2,3,4,5 |
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If set to 1 then a table of estimated values, based on the regression equation, will be written to the Command window. The default is (0), do not create the table. |
No |
0 |
0,1 |
0,1 |
Notes
No additional notes.
Example
In the following example, a regression line is calculated for estimating P2O5 field values from FE field values in file assays.
!POLREG &IN(ASSAYS),&OUT(COEFFS),*X(FE),*Y(P2O5),@ORDER=1
Error and Warning Messages
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Message |
Description |
Solution |
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>>> ORDER CANNOT BE LESS THAN 1, ORDER=1 HAS BEEN ASSUMED <<< |
A value of @ORDER below the minimum permitted value has been entered. The value is reset to the minimum and processing continues. |
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>>> ORDER CANNOT BE GREATER THAN 5, ORDER=5 HAS BEEN ASSUMED <<< |
A value of @ORDER above the maximum permitted value has been entered. The value is reset to the maximum and processing continues. |
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>>> FIELD nnnnnnnn IS NOT NUMERIC <<< >>> ERR 120 <<< ( fileno) IN POLREG |
Either the *X or *Y fields were not numeric. Fatal; the process is exited. |
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>>> TOO LITTLE DATA, CANNOT COMPUTE POLYNOMIAL OF REQUIRED ORDER <<< >>> ERR 120 <<< ( fileno) IN POLREG |
The minimum number of points required is @ORDER + 1. Fatal; the process is exited. |
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>>> ABSOLUTE VALUE OF DIV. IS LESS THAN OR EQUAL TO ZERO >>> ERR 501 <<< ( 0) IN DSLE |
The matrix of data presented for solution was singular. The data is inappropriate. Warning; the process continues, but the results may be meaningless. |
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