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Abteilung Astronomie

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defpar Source code in cafe_defpar.pro


           define model parameter properties like its name or its boundary
           defpar, parameter[:group],property,value
           parameter - The parameter to change. This can be either:
                        - The absolute parameter number in the
                          current model.
                        - A parameter number range, defined by the
                          first parameter and last parameter,
                          separated with "-". (e.g. 1-7)
                        - A string designating the parameter
                          name. The parameter name is usually
                          "model:parname". If this parameter name is
                          not unique in current model all matching
                          parameters will be asked to change.
                       If no parameter information is given all
                       parameters will be asked to changed.
               group - The group number defining the model to
                       change. Default is 0, must be in range [0,9].
            property - Which part of the parameter will be
                       changed. Currently valid properties are (these
                       are also mentioned in mpfitfun.pro):
                   VALUE - the starting parameter value.
                   FIXED - a boolean value, whether the parameter is to be held
                           fixed or not.
                 LIMITED - a two-element boolean array.  If the first/second
                           element is set, then the parameter is bounded on the
                           lower/upper side.  A parameter can be bounded on both
                           sides.  Both LIMITED and LIMITS must be given
                  LIMITS - a two-element float or double array.  Gives the
                           parameter limits on the lower and upper sides,
                           respectively.  Zero, one or two of these values can be
                           set, depending on the values of LIMITED.  Both LIMITED
                           and LIMITS must be given together.
                 PARNAME - name of the parameter.
                    STEP - the step size to be used in calculating the numerical
                           derivatives.  If set to zero, then the step size is
                           computed automatically.  Ignored when AUTODERIVATIVE=0.
                  MPSIDE - the sidedness of the finite difference when computing
                           numerical derivatives.  This field can take four
                            0 - one-sided derivative computed automatically
                            1 - one-sided derivative (f(x+h) - f(x)  )/h
                           -1 - one-sided derivative (f(x)   - f(x-h))/h
                            2 - two-sided derivative (f(x+h) - f(x-h))/(2*h)
                           Where H is the STEP parameter described above.  The
                           "automatic" one-sided derivative method will chose a
                           direction for the finite difference which does not
                           violate any constraints.  The other methods do not
                           perform this check.  The two-sided method is in
                           principle more precise, but requires twice as many
                           function evaluations.  Default: 0.
               MPMINSTEP - the minimum change to be made in the parameter
                           value.  During the fitting process, the parameter
                           will be changed by multiples of this value.
                           Note that this constraint should be used
                           with care since it may cause non-converging,
                           oscillating solutions.
                           A value of 0 indicates no minimum (  Default).
               MPMAXSTEP - the maximum change to be made in the parameter
                           value.  During the fitting process, the parameter
                           will never be changed by more than this value.
                           A value of 0 indicates no maximum (Default).
                    TIED - a string expression which "ties" the parameter to other
                           free or fixed parameters.  Any expression involving
                           constants and the parameter array P are permitted.
               value - The value to set the parameter property at.
           These properties are used for the fit command with the
           calling mpfit library functions. They also apply for the
           error command.
Side Effects
           Changes part of parameters.
               > defpar,sin:P:2, parname, period
                   sin:P: 22.5, 1
               -> changes Parameter name of sin:P of model in group 2 at "period"
Revision History
           $Id: cafe_defpar.pro,v 1.8 2003/11/05 15:10:44 goehler Exp $

Last modified by pro2html on 2005 January 04 at 16:03 UTC

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Jörn Wilms (wilms@astro.uni-tuebingen.de)
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