# Xvert: This function creates an extreme vertices design in a... In mixexp: Design and Analysis of Mixture Experiments

## Description

This function calls the function crvtave to create an extreme vertices design in a constrained mixture space. If there are only three factors the function DesignPoints is called to plot the results.

## Usage

 ```1 2 3 4``` ``` Xvert(nfac=3,uc=c(0,0),lc=c(0,0),nlc=0,lb=c(0,0),ub=c(0,0),coef,ndm=0,plot=TRUE, cornerlabs = c("x1","x2","x3"), axislabs = c("x1","x2","x3"), pseudo=TRUE) ```

## Arguments

 `nfac` an integer representing the number of mixture variables in the design. Maximum nfac=12 `uc` a vector of length nfac containing upper constraints on each mixture component `lc` a vector of length nfac containing lower constraints on each mixture component `nlc` the number of linear constraints, the default is zero `lb` a vector of length nlc containing the lower bounds for the linear constraints `ub` a vector of length nlc containing the upper bounds for the linear constraints `coef` an nlc by nfac matrix containing the coefficients of the components of the linear constraints `ndm` an integer representing the highest order of centroids requested. An overall centroid is always included, 0 indicates no other centroids will be created, 1 indicates edge centroids are requested, etc. `plot` a logical variable indicating whether a plot of the design is desired when there are only 3 components. Default is TRUE `cornerlabs` This is a vector of text labels for the x1, x2 and x3 vertices. Use when there are only 3 components for plotting. `axislabs` This is a vector of text labels for the x1, x2 and x3 axis. Use when there are only 3 components for plotting. `pseudo` logical variable, when TRUE plot in pseudo component space when there are lower constraints.

## Note

This function calls crvtave. If the number of factors is 3, the function DesignPoints is called to graph the results.

## Author(s)

John S. Lawson [email protected]

## References

1. Piepel, G. F. "Programs for Generating Extreme Vertices and Centroids of Linearly Consrtained Experimental Regions" Journal of Quality Technology, Vol 20, No. 2, pp. 125-139, 1988.

2. "John Lawson, Cameron Willden (2016).", "Mixture Experiments in R Using mixexp.", "Journal of Statistical Software, Code Snippets, 72(2), 1-20.", "doi:10.18637/jss.v072.c02"

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13``` ```# Polvoron Example from Lawson des<-Xvert(3,uc=c(.8,.95,.50),lc=c(0,.10,.05),ndm=1,plot=FALSE) #Snee Marquardt(1976) example Xvert(8,uc=c(.45,.50,.10,.4,.6,.2,.05,.05),lc=c(.1,.05,0,0,.1,.05,0,0),ndm=0) # Example page 465 exvert<-Xvert(4,uc=c(.188,.128,.438,.438),lc=c(.124,.064,.374,.374),ndm=2) # Example from Piepel 1988 coef<-matrix(c(.85,.9,1,.7,0,1),ncol=3,byrow=TRUE) des<-Xvert(3,lc=c(.1,.1,0),uc=c(.5,.7,.7),nlc=2,lb=c(.9,.4),ub=c(.95,0),coef,ndm=1,plot=FALSE) ```

mixexp documentation built on May 29, 2017, 7:09 p.m.