Resets all parameter names and values to undefined. Must normally be followed by a PARAMETER command or equivalent, in order to define parameter values.
Instructs MINUIT to trace contour lines of the user function with respect to the two parameters whose external numbers are par1 and par2. Other variable parameters of the function, if any, will have their values fixed at the current values during the contour tracing. The optional parameter devs (default value 2.) gives the number of standard deviations in each parameter which should lie entirely within the plotting area. Optional parameter ngrid (default value 25 unless page size is too small) determines the resolution of the plot, i.e. the number of rows and columns of the grid at which the function will be evaluated.
End of Interactive MINUIT. Control is returned to PAW.
Causes parameter parno to be removed from the list of variable parameters, and its value will remain constant (at the current value) during subsequent minimizations, etc., until another command changes its value or its status.
Causes MINUIT to list the available commands. The list of SET and SHOw commands must be requested separately.
Instructs MINUIT to calculate, by finite differences, the Hessian or error matrix. That is, it calculates the full matrix of second derivatives of the function with respect to the currently variable parameters, and inverts it, printing out the resulting error matrix. The optional argument maxcalls specifies the (approximate) maximum number of function calls after which the calculation will be stopped.
If a previous minimization has converged, and the current values of the parameters therefore correspond to a local minimum of the function, this command requests a search for additional distinct local minima. The optional argument maxcalls specifies the (approximate) maximum number of function calls after which the calculation will be stopped.
Causes minimization of the function by the method of Migrad, the most
efficient and complete single method, recommended for general functions
(see also MINImize).
The minimization produces as a by-product the error matrix
of the parameters, which is usually reliable unless warning messages
are produced.
The optional argument maxcalls specifies the (approximate) maximum
number of function calls after which the calculation will be stopped
even if it has not yet converged.
The optional argument tolerance specifies required tolerance on the
function value at the minimum.
The default tolerance is 0.1.
Minimization will stop when the estimated vertical distance to
the minimum (EDM) is less than 0.001* tolerance *UP
(see SET ERR
MINImize maxcalls tolerance
Causes minimization of the function by the method of Migrad, as does the MIGrad command, but switches to the SIMplex method if Migrad fails to converge. Arguments are as for MIGrad.
Causes a Minos error analysis to be performed on the parameters whose numbers parno are specified. If none are specified, Minos errors are calculated for all variable parameters. Minos errors may be expensive to calculate, but are very reliable since they take account of non-linearities in the problem as well as parameter correlations, and are in general asymmetric. The optional argument maxcalls specifies the (approximate) maximum number of function calls per parameter requested, after which the calculation will be stopped for that parameter.
If parno is the number of a previously variable parameter which has been fixed by a command: FIX parno, then that parameter will return to variable status. Otherwise a warning message is printed and the command is ignored. Note that this command operates only on parameters which were at one time variable and have been FIXed. It cannot make constant parameters variable; that must be done by redefining the parameter with a PARAMETER command.
If no code is specified, this command restores all previously FIXed parameters to variable status. If code =1, then only the last parameter FIXed is restored to variable status.
Scans the value of the user function by varying parameter number parno , leaving all other parameters fixed at the current value. If parno is not specified, all variable parameters are scanned in sequence. The number of points numpts in the scan is 40 by default, and cannot exceed 100. The range of the scan is by default 2 standard deviations on each side of the current best value, but can be specified as from from to to . After each scan, if a new minimum is found, the best parameter values are retained as start values for future scans or minimizations. The curve resulting from each scan is plotted on the output unit in order to show the approximate behaviour of the function. This command is not intended for minimization, but is sometimes useful for debugging the user function or finding a reasonable starting point.
Causes a Monte Carlo minimization of the function, by choosing random values of the variable parameters, chosen uniformly over a hypercube centered at the current best value. The region size is by default 3 standard deviations on each side, but can be changed by specifying the value of devs .
Sets the value of up (default value= 1.), defining parameter errors. MINUIT defines parameter errors as the change in parameter value required to change the function value by up. Normally, for chisquared fits up=1, and for negative log likelihood, up=0.5.
Allows the user to change the limits on one or all parameters. If no arguments are specified, all limits are removed from all parameters. If parno alone is specified, limits are removed from parameter parno . If all arguments are specified, then parameter parno will be bounded between lolim and uplim . Limits can be specified in either order, MINUIT will take the smaller as lolim and the larger as uplim . However, if lolim is equal to uplim , an error condition results.
Sets the value of parameter parno to value. The parameter in question may be variable, fixed, or constant, but must be defined.
Sets the print level, determining how much output MINUIT will produce. The allowed values and their meanings are displayed after a SHOw PRInt command. Possible values for level are:
Sets the strategy to be used in calculating first and second derivatives and in certain minimization methods. In general, low values of level mean fewer function calls and high values mean more reliable minimization. Currently allowed values are 0, 1 (default), and 2.
All SET XXXX commands have a corresponding SHOw XXXX command. In addition, the SHOw commands listed starting here have no corresponding SET command for obvious reasons. The full list of SHOw commands is printed in response to the command HELP SHOw.
Calculates and prints the parameter correlations from the error matrix.
Prints the (external) covariance (error) matrix.
Performs a function minimization using the simplex method of Nelder and
Mead. Minimization terminates either when the function has been called
(approximately) maxcalls times,
or when the estimated vertical
distance to minimum (EDM) is less than tolerance .
The default value of tolerance is
0.1*UP (see SET ERR