C-PLOT

Contents → Fitting → sp, sP, sf, sF save parameters

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The save parameters commands let you write out the current parameters to the screen or to a file in several formats.

sp
sp filename [a|w]
or
sP, sf and sF (same options)

With no arguments, sp, sP, sf and sF all write the current set of parameters to the screen in the same format as the last iteration of the fit. The meaning of the values printed is explained under the command fi. The commands sP and sF print out the calculated errors in the fitted parameters, rounding the fitted parameter values to two significant figures of the error. The commands sp and sf don't print the errors, but do print out six significant figures of each parameter.

With a filename argument, the format produced by these commands is quite different and is intended to be used with the annotation feature of the plot program. The command sp filename writes to the file:

\H@13@\W@-\(*x\u\s2\b\l\d @\(*x\u\s2\b\l\d = 1.088
\H@13@\W@-Constant term@Constant term = 10.2309 \(lh
\H@13@\W@-Linear term@Linear term = 4.01735 \(lh

which, when interpreted by C-PLOT by typing pn filename, writes on the plot:

The hand symbols indicate which were the fitted parameters.

The formatting sequences on the parameter lines will make the equals signs line up when used with the annotation command, even with nonproportional fonts. The delimiter character @ used in the formatting sequences cannot be used in your parameter names, without causing problems for the rp command and for the user function fitpar.4 described in Appendix C.


The command sP filename produces:

\H@13@\W@-\(*x\u\s2\b\l\d @\(*x\u\s2\b\l\d = 1.088
\H@13@\W@-Constant term@Constant term = 10.\(+-12.
\H@13@\W@-Linear term@Linear term = 4.02\(+-0.83

which, when interpreted by C-PLOT by typing pn filename, writes on the plot:



The command sF filename produces:

Fit 11 points with `line.5'
Fit to a line:  y = c + m * x
Statistical weights
Converged by \(*e test (\(*e = 0.001)
10 \(<= x \(<= 20
\H@13@\W@-\(*x\u\s2\b\l\d @\(*x\u\s2\b\l\d = 1.088
\H@13@\W@-Constant term@Constant term = 10.\(+-12.
\H@13@\W@-Linear term@Linear term = 4.02\(+-0.83

which, when interpreted by C-PLOT by typing pn filename, writes on the plot:

The first line includes the name of the fitting function. The second line is a comment set in the prototype file. The third line indicates the method of weighting. The fourth line shows how the fit terminated. The next line or lines show the range of each of the independent variables. (In this example there is just one.)

The output from sf filename is similar, but the errors are not printed with the parameters.

By indicating a or w after the file name, you tell the program either to append to the file or to write over the current contents of the file. If the file already exists, you must explicitly indicate you wish to write over the file, otherwise the file will not be changed.

The output format that appears on the screen also can be directed to a file using the >filename syntax, as explained in the notes to the list of commands at the beginning of this chapter.

The public user function fitpar.4, described in Appendix C, lets you read a file containing many parameter sets created using any of the save-parameter commands to produce plots of any parameter versus any other.

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