DSYSID

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
DSYSID	22	SYS	3	4	0.002
+			5	5	0.05

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
DRESP1	3	TZ488	DISP			3		488
DRESP1	5	TZ601	DISP			3		601

Field	Contents	SI Unit Example
`DOID`	Design objective identification number. (Integer > 0)
`LABEL`	User-defined name for the response. No default (Character)
`RIDi`	DRESP1, DRESP2, or DRESP3 identification number. (Integer > 0)
`SIDi`	Subcase identification number. ALL (Default) If it applies to all subcases. blank (Integer > 0)
`Ti`/`TIDi`	Target value or table identification number of a TABLEDi entry that specifies the target value as function of a loading frequency. No default (Real or Integer)
`Wi`/`WTIDi`	Weighting factor or table identification number of a TABLEDi entry that specifies the weighting factor as function of a loading frequency. Default = 1.0 (Real, Integer or blank)

If the DSYSID entry is referenced by a DESOBJ Subcase entry, a least squares objective function is used in the optimization. The objective function is the sum of the squared, weighted, normalized differences between the target responses and those calculated by the finite element analysis:(1)
$min {\sum_{i = 1}^{n} (W_{i} \frac{F_{i} - T_{i}}{T_{i}})}^{2}$
If the DSYSID entry is referenced by a MINMAX or MAXMIN Subcase Information Entry, the beta method is applied in the optimization as:(2)
$min β with W_{i} | \frac{F_{i} - T_{i}}{T_{i}} | \leq β$
DSYSID entries must have unique identification numbers with respect to DRESP1, DRESP2, and DRESP3 entries.
DRESP1, DRESP2, and DRESP3 entries referenced by the DSYSID entry can define only a single response per subcase when the DESOBJ formulation is used. There is no such limitation with the MINMAX or MAXMIN formulations.
In order to use DSCREEN to control the number of retained responses when performing a system identification, RTYPE=EQUA needs to be used on the DSCREEN entry.