FIT command
Syntax: |
FIT y = { expression } |
Qualifiers: |
\NORMAL, \POISSON, \UPDATE, \ITMAX, \WEIGHTS, \TOLERANCE, \ZEROS, \CHISQ,
\VARNAMES, \CORRMAT, \COVMAT, \CL, \E1, \E2, \FREE, \RESET, \MESSAGES |
Defaults: |
\NORMAL, \-ITMAX, \-WEIGHTS, \-TOLERANCE, \ZEROS, \-CHISQ, \-CL, \-VARNAMES,
\-CORRMAT, \-COVMAT, \-E1, \-E2, \-RESET, \-FREE, \MESSAGES |
Examples: |
FIT Y=A*X+B |
By default, or if the \NORMAL
qualifier is used,
it is assumed that each data point has an error that is distributed as a normal distribution,
where is the mean and
is the standard deviation of the distribution. The weight is defined as:
If the \POISSON
qualifier is used, the
data errors are assumed to be distributed as a Poisson distribution,
where is the mean and the variance of the distribution.
Expression and parameters
The expression
must result in a vector with the same length as
the data vector, y
. A maximum of twenty-five (25
) fitting parameters are
allowed in the expression
. The fitting parameter values are altered during the fit.
Fit parameters are created with the
SCALAR\FIT
command, and can be converted to fixed value scalars with the SCALAR
command. If you use
the \RESET
qualifier, the fitting parameters will be reset to their original values
after an unsuccessful fit.
If the \VARNAMES
qualifier is used with the FIT
command, a string array
variable named FIT$VAR
will be made which will contain the
names of the fitting parameter variables. The array length of FIT$VAR
will be equal to the number of fit parameters.
Informational messages
By default, information on the progress of the fit, as well as the results,
are displayed on the monitor screen. If the
\-MESSAGES
qualifier is used, these informational messages will be suppressed.
Method
Tolerance
Correlation and covariance
Confidence level
Number of iterations
Update after a fit
Normal distribution
Poisson distribution