A square grid containing sample positions is a Latin square if, and only if, there is
only one sample in each row and each column. A Latin HyperCubeDOE, categorized as a space filling DOE, is the generalization of this concept to an arbitrary number of
dimensions.
When sampling a design space of N variables, the range of each variable is divided
into M equally probable intervals. M sample points are then placed to satisfy the
Latin HyperCube requirements. As a result, all
experiments have unique levels for each input variable and the number of sample
points, M, is not a function of the number of input variables.Figure 1.
Figure 2 shows a Latin HyperCube (left) and
Hammersley (right) for 100 runs.Figure 2.
Usability Characteristics
To get a good quality fitting function, a minimum number of runs should be
evaluated. (N+1)(N+2)/2 runs are needed to fit a second order polynomial,
assuming that most output responses are close to a second order polynomial
within the commonly used input variable ranges of -+10%. An additional
number of runs equal to 10% is recommended to provide redundancy, which
results in more reliable post-processing. As a result, this equation is
recommend to calculate the number of runs needed or a minimum of
1.1*(N+1)(N+2)/2 runs.
The structure of a Latin HyperCube run matrix
ensures that the runs are orthogonal. Orthogonality is desirable because it
is less likely to result in singularities when creating Least Squares Regression fits.
Any data in the inclusion matrix is combined with the run data for
post-processing. Any run matrix point which is already part of the inclusion
data will not be rerun.
Settings
In the Specifications step, Settings tab, change method
settings.
Parameter
Default
Range
Description
Number of Runs
> 0 integer
Number of new designs to
be evaluated.
Random Seed
1
Integer
0 to 10000
Controlling repeatability of
runs depending on the way the sequence of random numbers is
generated.
0
Random (non-repeatable).
>0
Triggers a new sequence of pseudo-random numbers, repeatable
if the same number is specified.
Use Inclusion
Matrix
Off
Off or On
Concatenation without
duplication between the inclusion and the generated run matrix.