Up: FIT Language Internal Help
FIT\LINES [N [Guesses]] [/NOCURSOR] [/INPUT File_Name] [/SHOW]
Enter the initial values for the profile fit. If argument "AUTO" is
given instead of a number, then the number of lines found in the last
read spectrum will be used for ITERATE command.
If N is not specified, then the last value for N is used. If N is 0,
MINIMIZE will attempt to guess initial values for a single line by com-
puting the moments of the spectrum. If N is not 0, the user has to pro-
vide the initial values for line parameters. N is limited to 5. These
values should be separated by spaces and can be entered as SIC expres-
sions as follows:
Method Code,Value Code,Value Code,Value Code,Value
GAUSS Temperature Position Width
SHELL Area (K.MHz) Offset (MHz) Width (MHz) Horn/Center
NH3 Temperature Position Width (MHz) Opacity
HFS Temperature Position Width (MHz) Opacity
ABSORPTION Opacity Position Width
(no initial guess is needed for the continuum level)
The code is an integer interpreted as follows :
0 adjustable parameter
1 fixed parameter
2 adjustable parameter (head of group)
3 parameter fixed with respect to parameter coded 2 or 4
4 fixed parameter (head of group)
Codes 2 3 and 4 are used to fit dependent lines (e.g. HCN, for which the
displacements are 4.842 and -7.064 km/s, or -1.431 and 2.088 MHz, and
line ratios 1:0.6:0.2). Codes 0 and 1 only are allowed for NH3 method.
The value for a parameter with code 3 should be either the ratio to the
head of group value (for both intensity and width), or the offset from
head of group (for the position).
There are 4 possibilities for the user to provide the line parameters:
- If /INPUT File_Name is used, guesses are read from the input file.
"Free" format is used to read in this input file. The first line
must contain the number of lines, others are as the input at the
- The guesses can also be entered from the command line, as double-
quoted strings, one per line, e.g.
FIT\LINES 2 "0 0.20 0 0.00 0 25.00" "0 0.10 0 0.00 0 50.00"
- If the cursor is available, you will have to set interactively on
the plot the boundaries of the N lines. The program then computes
the moments of the spectra between these boundaries as input values.
You cannot change the codes in this way which is meaningfull ONLY
FOR FREE and INDEPENDENT lines. This cursor selection is not used if
you specify the /NOCURSOR option.
- If none of the 3 methods above is used, then the user is prompted in
the terminal for the guesses. The parameters must be entered togeth-
er, separated by blanks, one set of guesses per line.
The option /SHOW can be used for a feedback of what initial guesses have
just been defined.
Command LINES is not supported for method CONTINUUM.