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This command writes the current values of the fit parameters into the given file, formatted as an initial-value file (as described in the fitsection). This is useful for saving the current values for later use or for restarting a converged or stopped fit.


     update <filename> {<filename>}

If a second filename is supplied, the updated values are written to this file, and the original parameter file is left unmodified.

Otherwise, if the file already exists, gnuplot first renames it by appending .old and then opens a new file. That is, "update 'fred'" behaves the same as "!rename fred fred.old; update 'fred.old' 'fred'". [On DOS and other systems that use the twelve-character "filename.ext" naming convention, "ext" will be "old" and "filename" will be related (hopefully recognizably) to the initial name. Renaming is not done at all on VMS systems, since they use file-versioning.]

Please see fit for more information.

Several graphical user interfaces have been written for gnuplot and one for win32 is included in this distribution. In addition, there is a Macintosh interface at


and several X11 interfaces include three Tcl/Tk located at the usual Tcl/Tk repositories.

Floating point exceptions (floating point number too large/small, divide by zero, etc.) may occasionally be generated by user defined functions. Some of the demos in particular may cause numbers to exceed the floating point range. Whether the system ignores such exceptions (in which case gnuplot labels the corresponding point as undefined) or aborts gnuplot depends on the compiler/runtime environment.

The bessel functions do not work for complex arguments.

The gamma function does not work for complex arguments.

As of gnuplot version 3.7, all development has been done using ANSI C. With current operating system, compiler, and library releases, the OS specific bugs documented in release 3.5, now relegated to old_bugs, may no longer be relevant.

Bugs reported since the current release may be located via the official distribution site:


Please e-mail any bugs to bug-gnuplot@dartmouth.edu.

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