Produces a star point design of experiments
H = scidoe_star(nbvar) [H, a] = scidoe_star(nbvar) H = scidoe_star(nbvar,"Name",value) [H, a] = scidoe_star(nbvar,"Name",value)
a 1-by-1 matrix of doubles, positive integer, the number of variables of the experiments
a 1-by-1 matrix of strings. The options are "alpha" and "center".
the value
a 2*nbvar-by-nbvar matrix of doubles, the design of experiments
a 1-by-1 matrix of doubles, a positive integer, the value of alpha
This function computes a star points design of experiments, used as an additional block of runs in Response Surface Designs (RSM). Each factor is sequentially placed at +/-alpha, while all other factors are at zero. The value of alpha is determined by the user to give the design desirable properties.
The available options are the following.
"alpha" : "orthogonal", "rotatable" or "faced" (default).
"center" : a 1-by-2 row vector of doubles, positive integers, indicating the number of center points assigned in each block of the response surface design. Default is [1 1].
A RSM design includes a factorial block of exeprimental runs and a block of center points. These points are used to calculate alpha, as follows0
If the design is "orthogonal",
alpha = sqrt(nbvar*(1+(nao/na))/(1+(nco/nc))),
nc : the number of factorial points,
nco : the number of center points added to the factorial design,
na : the number of axial points,
nao : the number of center points added to the axial points.
If the design is rotatable,
alpha = nc^1/4,
If the design is "faced", then alpha=1.
The center points is a 1-by-2 row vector of doubles, positive integers, indicating the number of center points assigned in each block of the response surface design. The default number of center points is [1,1], meaning 1 center point in the factorial block of the doe and 1 center point in the star points block. Setting the number of center points is meaningful only for the "orthogonal" design.
http://en.wikipedia.org/wiki/Central_composite_design
http://www.itl.nist.gov/div898/handbook/pri/section3/pri3361.htm