Variable Parameters

A parameter to be varied is specified by the command:

VARY,NAME=variable,STEP=real,LOWER=real,UPPER=real;

It has four attributes:

NAME: The name of the parameter or attribute to be varied.

STEP: The approximate initial step size for varying the parameter. If the step is not entered, MAD tries to find a reasonable step, but this may not always work.

LOWER: Lower limit for the parameter (optional),

UPPER: Upper limit for the parameter (optional).

Upper and/or lower limits can also be imposed via the CONSTRAINT command, which is usually faster than entering limits on the VARY command. Examples:

VARY,PAR1,STEP=1.0E-4       // vary global parameter PAR1 
VARY,QL11->K1,STEP=1.0E-6   // vary attribute K1 of the QL11 
VARY,Q15->K1,STEP=0.0001,LOWER=0.0,UPPER=0.08 // vary with limits

If the upper limit is smaller than the lower limit, the two limits are interchanged. If the current value is outside the range defined by the limits, it is brought back to range. After a matching operation all varied attributes retain their last value. They are never reset to an old value. If a matching variable depends on another variable, this dependency is broken by the VARY command. Example:

P1:=10.0-P2

Both P1 and P2 may be varied. If P1 is varied however, its dependence on P2 is broken.