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robeth (version 2.7-8)

robeth-package: Interface for the FORTRAN programs developed at the ETH-Zuerich and then at IUMSP-Lausanne

Description

This package allows the computation of a broad class of procedures based on M-estimation and high breakdown point estimation, including robust regresion, robust testing of linear hypotheses and robust covariances. The reference book quoted below is required for the theoritical background of the statistical and numerical methods

Arguments

Author

Alfio Marazzi <Alfio.Marazzi@chuv.ch>

Maintainer: A. Randriamiharisoa <Alex.Randriamiharisoa@chuv.ch>

Details

Package:robeth
Type:Package
#Version:2.7-7
#Date:2023-06-19
License:GPL version 2 or later

References

Marazzi A., (1993) Algorithm, Routines, and S functions for Robust Statistics. Wadsworth & Brooks/cole, Pacific Grove, California.

Examples

Run this code
library(robeth)

#
# ------------- Examples of Chapter 1: Location problems ------------------------------
#
 y  <- c(6.0,7.0,5.0,10.5,8.5,3.5,6.1,4.0,4.6,4.5,5.9,6.5)
 n  <- 12
 dfvals()
#-----------------------------------------------------------------------
# M-estimate (tm) of location and confidence interval (tl,tu)
#
 dfrpar(as.matrix(y),"huber")
 libeth()
 s  <- lilars(y);  t0 <- s$theta;  s0 <- s$sigma
 s  <- lyhalg(y=y,theta=t0,sigmai=s0)
 tm <- s$theta;    vartm <- s$var
 s  <- quant(0.975)
 tl <- tm-s$x*sqrt(vartm)
 tu <- tm+s$x*sqrt(vartm)
#-----------------------------------------------------------------------
# Hodges and Lehmann estimate (th) and confidence interval (zl,zu)
# 
 m  <- n*(n+1)/2 # n even
 k1 <- m/2; k2 <- k1+1
 z1 <- lyhdle(y=y,k=k1);   z2 <- lyhdle(y=y,k=k2)
 th <- (z1$hdle+z2$hdle)/2.
 ku <- liindh(0.95,n);     kl <- liindh(0.05,n)
 zu <- lyhdle(y=y,k=ku$k); zl <- lyhdle(y=y,k=kl$k)
#.......................................................................
{
 cat(" tm, tl, tu : ",round(c(tm,tl,tu),3),"\n")
 cat(" th, zl, zu : ",round(c(th,zl$hdle,zu$hdle),3),"\n")
}
#  tm, tl, tu : 5.809 4.748 6.87 
#  th, zl, zu : 5.85 5 7 
#=======================================================================
#
# Two sample problem
#
 y <- c(17.9,13.3,10.6,7.6,5.7,5.6,5.4,3.3,3.1,0.9)
 n <- 10
 x <- c(7.7,5.0,1.7,0.0,-3.0,-3.1,-10.5)
 m <- 7
#-----------------------------------------------------------------------
# Estimate (dm) and confidence interval [dl,du] based on Mann-Whitney
#
 k1 <- m*n/2;  k2 <- k1+1
 s1 <- lymnwt(x=x,y=y,k=k1);       s2 <- lymnwt(x=x,y=y,k=k2)
 dm <- (s1$tmnwt+s2$tmnwt)/2.0
 sl <- liindw(0.05,m,n);           kl <- sl$k
 s  <- lymnwt(x=x,y=y,k=kl);       dl <- s$tmnwt
 s  <- lymnwt(x=x,y=y,k=m*n-kl+1); du <- s$tmnwt
#-----------------------------------------------------------------------
# Tau-test . P-value (P)
#
 z <- c(x,y)
 dfrpar(as.matrix(z),"huber")
 libeth()
 s <- lytau2(z=z,m=m,n=n)    
 P <- s$p
#
# estimate (tm) and confidence interval (tl,tu)
#
 tm <- s$deltal
 c22<- s$cov[3]
 s  <- quant(0.975)
 tl <- tm-s$x*sqrt(c22)
 tu <- tm+s$x*sqrt(c22)
#.......................................................................
{
 cat("dm, dl, du:",round(c(dm,dl,du),3),"\n")
 cat("P, tm, tl, tu:",round(c(P,tm,tl,tu),3),"\n")
}
# dm, dl, du: 6.35 2.9 12.9 
# P, tm, tl, tu: 0.014 6.918 1.562 12.273 

#
# Examples of Chapter 2: M-estimates of coefficients and scale in linear regression
#
# Read data; declare the vector wgt; load defaults
#
 z <- c(-1, -2,  0,   35,         1,  0, -3,   20, 
        -1, -2,  0,   30,         1,  0, -3,   39,
        -1, -2,  0,   24,         1,  0, -3,   16,
        -1, -2,  0,   37,         1,  0, -3,   27,
        -1, -2,  0,   28,         1,  0, -3,  -12,
        -1, -2,  0,   73,         1,  0, -3,    2,
        -1, -2,  0,   31,         1,  0, -3,   31,
        -1, -2,  0,   21,         1,  0, -1,   26,
        -1, -2,  0,   -5,         1,  0, -1,   60,
        -1,  0,  0,   62,         1,  0, -1,   48,
        -1,  0,  0,   67,         1,  0, -1,   -8,
        -1,  0,  0,   95,         1,  0, -1,   46,
        -1,  0,  0,   62,         1,  0, -1,   77,
        -1,  0,  0,   54,         1,  0,  1,   57,
        -1,  0,  0,   56,         1,  0,  1,   89,
        -1,  0,  0,   48,         1,  0,  1,  103,
        -1,  0,  0,   70,         1,  0,  1,  129,
        -1,  0,  0,   94,         1,  0,  1,  139,
        -1,  0,  0,   42,         1,  0,  1,  128,
        -1,  2,  0,  116,         1,  0,  1,   89,
        -1,  2,  0,  105,         1,  0,  1,   86,
        -1,  2,  0,   91,         1,  0,  3,  140,
        -1,  2,  0,   94,         1,  0,  3,  133,
        -1,  2,  0,  130,         1,  0,  3,  142,
        -1,  2,  0,   79,         1,  0,  3,  118,
        -1,  2,  0,  120,         1,  0,  3,  137,
        -1,  2,  0,  124,         1,  0,  3,   84,
        -1,  2,  0,   -8,         1,  0,  3,  101)
  xx    <- matrix(z,ncol=4, byrow=TRUE)
  dimnames(xx) <- list(NULL,c("z2","xS","xT","y"))
  z2    <- xx[,"z2"]; xS <- xx[,"xS"]; xT <- xx[,"xT"]
  x     <- cbind(1, z2, xS+xT, xS-xT, xS^2+xT^2, xS^2-xT^2, xT^3)
  y     <- xx[,"y"]
  wgt   <- vector("numeric",length(y))
  n     <- 56; np <- 7
  dfvals()
# Set parameters for Huber estimate
  dfrpar(x, "huber")
# Compute the constants beta, bet0, epsi2 and epsip
  ribeth(wgt)
  ribet0(wgt)
  s     <- liepsh()
  epsi2 <- s$epsi2;    epsip <- s$epsip
#
# Least squares solution (theta0,sigma0)
#
  z     <- riclls(x, y)
  theta0<- z$theta; sigma0 <- z$sigma
# Preliminary estimate of the covariance matrix of the coefficients
  cv    <- kiascv(z$xt, fu=epsi2/epsip^2, fb=0.)
  cov   <- cv$cov
#-----------------------------------------------------------------------
# Solution (theta1,sigma1) by means of RYHALG.
#
  zr    <- ryhalg(x,y,theta0,wgt,cov,sigmai=sigma0,ic=0)
  theta1<- zr$theta[1:np]; sigma1 <- zr$sigmaf; nit1 <- zr$nit
#-----------------------------------------------------------------------
# Solution (theta2,sigma2) by means of RYWALG (recompute cov) 
#
  cv <- ktaskv(x, f=epsi2/epsip^2)
  zr <- rywalg(x, y, theta0, wgt, cv$cov, sigmai=sigma0)
  theta2 <- zr$theta[1:np]; sigma2 <- zr$sigmaf; nit2 <- zr$nit
#-----------------------------------------------------------------------
# Solution (theta3,sigma3) by means of RYSALG with ISIGMA=2.
#
  zr <- rysalg(x,y, theta0, wgt, cv$cov, sigma0, isigma=2)
  theta3 <- zr$theta[1:np]; sigma3 <- zr$sigmaf; nit3 <- zr$nit
#-----------------------------------------------------------------------
# Solution (theta4,sigma4) by means of RYNALG with ICNV=2 and ISIGMA=0.
#
# Invert cov
  covm1 <- cv$cov
  zc <- mchl(covm1,np)
  zc <- minv(zc$a, np)
  zc <- mtt1(zc$r,np)
  covm1 <- zc$b
  zr <- rynalg(x,y, theta0, wgt, covm1, sigmai=sigma3,
        iopt=1, isigma=0, icnv=2)
  theta4 <- zr$theta[1:np]; sigma4 <- zr$sigmaf; nit4 <- zr$nit
#.......................................................................
{
  cat("theta0 : ",round(theta0[1:np],3),"\n")
  cat("sigma0 : ",round(sigma0,3),"\n")
  cat("theta1 : ",round(theta1,3),"\n")
  cat("sigma1, nit1 : ",round(sigma1,3),nit1,"\n")
  cat("theta2 : ",round(theta2,3),"\n")
  cat("sigma2, nit2 : ",round(sigma2,3),nit2,"\n")
  cat("theta3 : ",round(theta3,3),"\n")
  cat("sigma3, nit3 : ",round(sigma3,3),nit3,"\n")
  cat("theta4 : ",round(theta4,3),"\n")
  cat("sigma4, nit4 : ",round(sigma4,3),nit4,"\n")
}
# theta0 :  68.634 3.634 24.081 -8.053 -0.446 -0.179 -1.634 
# sigma0 :  26.635 
# theta1 :  70.006 5.006 24.742 -6.246 -0.079 0.434 -1.487 
# sigma1, nit1 :  23.564 7 
# theta2 :  70.006 5.006 24.742 -6.245 -0.079 0.434 -1.487 
# sigma2, nit2 :  23.563 7 
# theta3 :  69.993 5.002 24.766 -6.214 -0.055 0.44 -1.48 
# sigma3, nit3 :  22.249 3 
# theta4 :  69.993 5.002 24.766 -6.214 -0.055 0.44 -1.48 
# sigma4, nit4 :  22.249 3 


#
# ---- Examples of Chapter 3: Weights for bounded influence regression ------
#

#=======================================================================
 rbmost <- function(x,y,cc,usext=userfd) {
 n      <- nrow(x); np <- ncol(x); dfcomn(xk=np)
 .dFvPut(1,"itw")
 z      <- wimedv(x)
 z      <- wyfalg(x, z$a, y, exu=usext); nitw <- z$nit
 wgt    <- 1/z$dist; wgt[wgt>1.e6] <- 1.e6
 z      <- comval()
 bto    <- z$bt0;    ipso   <- z$ipsi; co <- z$c
 z      <- ribet0(wgt, itype=2, isqw=0)
 xt     <- x*wgt;    yt     <- y * wgt
 z      <- rilars(xt, yt)
 theta0 <- z$theta;  sigma0 <- z$sigma
 rs     <- z$rs/wgt; r1     <- rs/sigma0 
 dfcomn(ipsi=1,c=cc)
 z      <- liepsh(cc)
 den    <- z$epsip
 g      <- Psp(r1)/den # (see Psi in Chpt. 14)
 dfcomn(ipsi=ipso, c=co, bet0=bto)
 list(theta=theta0, sigma=sigma0, rs=rs, g=g, nitw=nitw)
}
#-----------------------------------------------------------------------
# Mallows-standard estimate (with wyfalg and rywalg)
#
 Mal.Std <- function(x, y, b2=-1, cc=-1, isigma=2) {
 n <- length(y); np <- ncol(x)
 dfrpar(x, "Mal-Std", b2, cc); .dFv <- .dFvGet()
 if (isigma==1) {dfcomn(d=.dFv$ccc); .dFvPut(1,"isg")}
# Weights 
 z      <- wimedv(x)
 z      <- wyfalg(x, z$a, y); nitw <- z$nit
 wgt    <- Www(z$dist)   # See Www in Chpt. 14
# Initial cov. matrix of coefficient estimates
 z      <- kiedch(wgt)
 cov    <- ktaskw(x, z$d, z$e, f=1/n)
# Initial theta and sigma
 z      <- rbmost(x,y,1.5,userfd)
 theta0 <- z$theta; sigma0 <- z$sigma; nitw0 <- z$nitw
# Final theta and sigma
 if (isigma==1) ribeth(wgt) else ribet0(wgt)
 z      <- rywalg(x, y,theta0,wgt,cov$cov, sigmai=sigma0)
 theta1 <- z$theta[1:np]; sigma1 <- z$sigmaf; nit1 <- z$nit
# Covariance matrix of coefficient estimates
 z      <- kfedcc(wgt, z$rs, sigma=sigma1)
 cov    <- ktaskw(x, z$d, z$e, f=(sigma1^2)/n)
 sd1    <- NULL; for (i in 1:np) { j <- i*(i+1)/2
 sd1    <- c(sd1,cov$cov[j]) }
 sd1    <- sqrt(sd1)
#.......................................................................
{
  cat("rbmost: theta0 : ",round(theta0[1:np],3),"\n")
  cat("rbmost: sigma0, nitw : ",round(sigma0,3),nitw0,"\n")
  cat("Mallows-Std: theta1 : ",round(theta1,3),"\n")
  cat("Mallows-Std: sd1    : ",round(sd1,3),"\n")
  cat("Mallows-Std: sigma1, nitw, nit1 : ",round(sigma1,3),nitw,nit1,"\n")
}

#.......................................................................
 list(theta0=theta0[1:np], sigma0=sigma0, nitw=nitw,
      theta1=theta1, sigma1=sigma1, nit1=nit1, sd1=sd1)}
#-----------------------------------------------------------------------
# Krasker-Welsch estimate (with wynalg and rynalg)
#
 Kra.Wel <- function(x, y, ckw=-1, isigma=2) {
 n <- length(y); np <- ncol(x)
 dfrpar(x, "Kra-Wel", ckw); .dFv <- .dFvGet()
 if (isigma==1) {dfcomn(d=.dFv$ccc); .dFvPut(1,"isg")}
# Weights 
 z      <- wimedv(x)
 z      <- wynalg(x, z$a); nitw <- z$nit
 wgt    <- Www(z$dist)  # See Www in Chpt. 14
# Initial cov. matrix of coefficient estimates
 z      <- kiedch(wgt)
 cov    <- ktaskw(x, z$d, z$e, f=1/n)
# Initial theta and sigma
 z      <- rbmost(x, y, cc=1.5)
 theta0 <- z$theta;       sigma0 <- z$sigma; nitw0 <- z$nitw
# Final theta and sigma
  if (isigma==1) ribeth(wgt) else ribet0(wgt)
 z      <- rynalg(x, y,theta0,wgt,cov$cov, sigmai=sigma0)
 theta2 <- z$theta[1:np]; sigma2 <- z$sigma; nit2 <- z$nit
#
# Covariance matrix of coefficient estimates
#
 z      <- kfedcc(wgt, z$rs, sigma=sigma2)
 cov    <- ktaskw(x, z$d, z$e, f=(sigma2^2)/n)
 sd2    <- NULL; for (i in 1:np) { j <- i*(i+1)/2
 sd2    <- c(sd2,cov$cov[j]) }
 sd2    <- sqrt(sd2)
#.......................................................................
{
  cat("rbmost: theta0 : ",round(theta0[1:np],3),"\n")
  cat("rbmost: sigma0, nitw : ",round(sigma0,3),nitw0,"\n")
  cat("Krasker-Welsch: theta2 : ",round(theta2,3),"\n")
  cat("Krasker-Welsch: sd2    : ",round(sd2,3),"\n")
  cat("Krasker-Welsch: sigma2, nitw, nit2 : ",round(sigma2,3),nitw,nit2,"\n")
}
#.......................................................................
 list(theta0=theta0[1:np], sigma0=sigma0, nitw=nitw,
      theta2=theta2, sigma2=sigma2, nit2=nit2, sd2=sd2)}
#-----------------------------------------------------------------------
# Read data; load defaults
# 
  z <- c( 8.2,  4, 23.005,  1,   7.6,  5, 23.873,  1,
          4.6,  0, 26.417,  1,   4.3,  1, 24.868,  1,
          5.9,  2, 29.895,  1,   5.0,  3, 24.200,  1,
          6.5,  4, 23.215,  1,   8.3,  5, 21.862,  1,
         10.1,  0, 22.274,  1,  13.2,  1, 23.830,  1,
         12.6,  2, 25.144,  1,  10.4,  3, 22.430,  1,
         10.8,  4, 21.785,  1,  13.1,  5, 22.380,  1,
         13.3,  0, 23.927,  1,  10.4,  1, 33.443,  1,
         10.5,  2, 24.859,  1,   7.7,  3, 22.686,  1,
         10.0,  0, 21.789,  1,  12.0,  1, 22.041,  1,
         12.1,  4, 21.033,  1,  13.6,  5, 21.005,  1,
         15.0,  0, 25.865,  1,  13.5,  1, 26.290,  1,
         11.5,  2, 22.932,  1,  12.0,  3, 21.313,  1,
         13.0,  4, 20.769,  1,  14.1,  5, 21.393,  1)
 x      <- matrix(z, ncol=4, byrow=TRUE)
 y      <- c( 7.6,  7.7,  4.3,  5.9,  5.0,  6.5,  8.3,  8.2, 13.2, 12.6,
             10.4, 10.8, 13.1, 12.3, 10.4, 10.5,  7.7,  9.5, 12.0, 12.6,
             13.6, 14.1, 13.5, 11.5, 12.0, 13.0, 14.1, 15.1)
 dfvals()
 dfcomn(xk=4)
 cat("Results\n")
 z1     <- Mal.Std(x, y)
 z2     <- Kra.Wel(x, y)


#
# ---- Examples of Chapter 4: Covariance matrix of the coefficient estimates ------
#

#
# Read x[1:4] and then set x[,4] <- 1
# 
 z     <- c(80, 27, 89, 1,   80, 27, 88, 1,   75, 25, 90, 1,
            62, 24, 87, 1,   62, 22, 87, 1,   62, 23, 87, 1,
            62, 24, 93, 1,   62, 24, 93, 1,   58, 23, 87, 1,
            58, 18, 80, 1,   58, 18, 89, 1,   58, 17, 88, 1,
            58, 18, 82, 1,   58, 19, 93, 1,   50, 18, 89, 1,
            50, 18, 86, 1,   50, 19, 72, 1,   50, 19, 79, 1,
            50, 20, 80, 1,   56, 20, 82, 1,   70, 20, 91, 1)
 x     <- matrix(z, ncol=4, byrow=TRUE)
 n     <- 21; np <- 4; ncov <- np*(np+1)/2
 dfvals()
# Cov. matrix of Huber-type estimates
 dfrpar(x, "huber")
 s     <- liepsh()
 epsi2 <- s$epsi2; epsip <- s$epsip
 z     <- rimtrf(x)
 xt    <- z$x; sg <- z$sg; ip <- z$ip
 zc    <- kiascv(xt, fu=epsi2/epsip^2, fb=0.)
 covi  <- zc$cov  # Can be used in ryhalg with ic=0
 zc    <- kfascv(xt, covi, f=1, sg=sg, ip=ip)
 covf  <- zc$cov
#.......................................................................
  str <- rep("  ", ncov); str[cumsum(1:np)] <- "\n"
{
  cat("covf:\n")
  cat(round(covf,6),sep=str)
}


#
# ---- Examples of Chapter 5: Asymptotic relative efficiency ------
#
#-----------------------------------------------------------------------
# Huber
#
    dfcomn(ipsi=1,c=1.345,d=1.345)
    .dFvPut(1,"ite")
    z <- airef0(mu=3, ialfa=1, sigmx=1)
#.......................................................................
{
   cat(" airef0 : Huber\n reff, alfa, beta, nit: ")
   cat(round(c(z$reff,z$alfa,z$beta,z$nit),3),sep=c(", ",", ",", ","\n"))
}
#-----------------------------------------------------------------------
# Schweppe: Krasker-Welsch
#
    dfcomn(ipsi=1,c=3.76,iucv=3,ckw=3.76,iwww=1)
    .dFvPut(3,"ite")
    z <- airef0(mu=3, ialfa=1, sigmx=1)
#.......................................................................
{
   cat(" airef0 : Krasker-Welsch\n reff, alfa, beta, nit: ")
   cat(round(c(z$reff,z$alfa,z$beta,z$nit),3),sep=c(", ",", ",", ","\n"))
}
#-----------------------------------------------------------------------
# Mallows-Standard
#
    dfcomn(ipsi=1,c=1.5,iucv=1,a2=0,b2=6.16,iww=3)
    .dFvPut(2,"ite")
    z <- airef0(mu=3, ialfa=1, sigmx=1)
#.......................................................................
{
   cat(" airef0 : Mallows-Std \n reff, alfa, beta, nit: ")
   cat(round(c(z$reff,z$alfa,z$beta,z$nit),3),sep=c(", ",", ",", ","\n"))
}
#=======================================================================
 z <- c(1, 0, 0,
        1, 0, 0,
        1, 0, 0,
        1, 0, 0,
        0, 1, 0,
        0, 1, 0,
        0, 1, 0,
        0, 1, 0,
        0, 0, 1,
        0, 0, 1,
        0, 0, 1,
        0, 0, 1)
 tt <- matrix(z,ncol=3,byrow=TRUE)
 n <- nrow(tt); mu <- 2
 nu <- ncol(tt)

#-----------------------------------------------------------------------
# Huber
#
    dfrpar(tt,"Huber")
    z <- airefq(tt, mu=mu, sigmx=1)
#.......................................................................
{
   cat(" airefq : Huber\n reff, beta, nit: ")
   cat(round(c(z$reff,z$beta,z$nit),3),sep=c(", ",", ",", ","\n"))
}
#-----------------------------------------------------------------------
# Krasker-Welsch
#
    dfrpar(tt,"kra-wel",upar=3.755)
    z <- airefq(tt, mu=mu, sigmx=1,init=1)
#.......................................................................
{
   cat(" airefq : Krasker-Welsch\n reff, beta, nit: ")
   cat(round(c(z$reff,z$beta,z$nit),3),sep=c(", ",", ",", ","\n"))
}
#-----------------------------------------------------------------------
# Mallows Standard
#
    dfrpar(tt,"Mal-Std",1.1*(mu+nu),1.569)
    z <- airefq(tt, mu=mu, sigmx=1,init=1)
#.......................................................................
{
   cat(" airefq : Mallows-Std\n reff, beta, nit: ")
   cat(round(c(z$reff,z$beta,z$nit),3),sep=c(", ",", ",", ","\n"))
}



#
# ---- Examples of Chapter 6: Robust testing in linear models ------
#

#=======================================================================
 tautest <- function(x,y,np,nq) {
# Full model. np variables in x[,1:np]
 n      <- nrow(x)
 z      <- riclls(x[,1:np], y)
 theta0 <- z$theta; sigma0 <- z$sigma; .dFv <- .dFvGet() 
 z      <- liepsh(.dFv$ccc) # ccc is globally defined by dfrpar
 epsi2  <- z$epsi2; epsip <- z$epsip
 zc     <- ktaskv(x[,1:np],f=epsi2/(epsip^2))
 covi   <- zc$cov
 ribeth(y) 
 zf     <- rywalg(x[,1:np],y,theta0,y,covi,sigmai=sigma0)
 thetaf <- zf$theta; sigma <- zf$sigmaf; rf <- zf$rs
 f      <- kffacv(rf,np=np,sigma=sigma)
 zc     <- ktaskv(x[,1:np],f=f$fh*(sigma^2)/n)
 cov    <- zc$cov
# Sub-model: nq variables in x[,1:nq], nq < np
 covi   <- cov[1:(nq*(nq+1)/2)]
 zs     <- rywalg(x[,1:nq], y, thetaf, y, covi, sigmai=sigma,isigma=0)
 thetas <- zs$theta; rs <- zs$rs
# Compute Tau-test statistic and P-value
 ztau   <- tftaut(rf,rs,y,rho,np,nq,sigma)
 ftau   <- ztau$ftau
 z      <- chisq(1,np-nq,ftau*epsip/epsi2)
 P      <- 1-z$p
#.......................................................................
{
 cat(" F_tau, P, sigma: ")
 cat(round(c(ftau,P,sigma),3),sep=c(", ",", ","\n"))
 cat(" theta (small model): ",round(thetas[1:nq],3),"\n\n")
}
#.......................................................................
 list(thetas=thetas[1:nq], sigma=sigma, rs=rs,ftau=ftau, P=P)}
#------------------------------------------------------------------------
 dshift <- function(x, theta, sigma, rs, nq) {
# Shift estimate d and confidence interval
 ncov   <- nq*(nq+1)/2
 f      <- kffacv(rs,np=nq,sigma=sigma)
 zc     <- ktaskv(x[,1:nq],f=f$fh)
 cov    <- zc$cov
 k11    <- 4.*cov[ncov-nq]
 k12    <- 2.*cov[ncov-1]
 k22    <- cov[ncov]
 za     <- quant(0.05/2)
 d      <- 2*theta[nq-1]/theta[nq]
 q      <- za$x*sigma/theta[nq]
 g      <- k22*(q^2)
 a      <- d-g*k12/k22
 b      <- abs(q)*sqrt(k11-2*d*k12+d*d*k22-g*(k11-k12*k12/k22))
 dL     <- (a-b)/(1-g)
 dU     <- (a+b)/(1-g)
#.......................................................................
 cat(" d, dL, dU: ",round(c(d,dL,dU),3),sep=c("",", ",", ","\n"))
#.......................................................................
 list(d=d, dL=dL, dU=dU)
}
#------------------------------------------------------------------------
 potcy  <- function(m,ml,mu,h,k,d,cs,ct) {
 fact   <- ((h*k) %% 2) + 1
 r      <- exp(log(d)*(fact*m+h-k)/2 - log(ct/cs))
 rl     <- exp(log(d)*(fact*ml+h-k)/2 - log(ct/cs))
 ru     <- exp(log(d)*(fact*mu+h-k)/2 - log(ct/cs))
 list(R=r, Rl=rl, Ru=ru)}
#------------------------------------------------------------------------
 rbmost <- function(x,y,cc,usext=userfd) {
 n      <- nrow(x); np <- ncol(x); dfcomn(xk=np)
 .dFvPut(1,"itw")
 z      <- wimedv(x)
 z      <- wyfalg(x, z$a, y, exu=usext); nitw <- z$nit
 wgt    <- 1/z$dist; wgt[wgt>1.e6] <- 1.e6
 z      <- comval()
 bto    <- z$bt0;    ipso   <- z$ipsi; co <- z$c
 z      <- ribet0(wgt, itype=2, isqw=0)
 xt     <- x*wgt;    yt     <- y * wgt
 z      <- rilars(xt, yt)
 theta0 <- z$theta;  sigma0 <- z$sigma
 rs     <- z$rs/wgt; r1     <- rs/sigma0 
 dfcomn(ipsi=1,c=cc)
 z      <- liepsh(cc)
 den    <- z$epsip
 g      <- Psp(r1)/den # (see Psp in Chpt. 14)
 dfcomn(ipsi=ipso, c=co, bet0=bto)
 list(theta=theta0, sigma=sigma0, rs=rs, g=g, nitw=nitw)
}
#=======================================================================
 dfvals()
 z <- c(-1, -2,  0,   35,         1,  0, -3,   20, 
        -1, -2,  0,   30,         1,  0, -3,   39,
        -1, -2,  0,   24,         1,  0, -3,   16,
        -1, -2,  0,   37,         1,  0, -3,   27,
        -1, -2,  0,   28,         1,  0, -3,  -12,
        -1, -2,  0,   73,         1,  0, -3,    2,
        -1, -2,  0,   31,         1,  0, -3,   31,
        -1, -2,  0,   21,         1,  0, -1,   26,
        -1, -2,  0,   -5,         1,  0, -1,   60,
        -1,  0,  0,   62,         1,  0, -1,   48,
        -1,  0,  0,   67,         1,  0, -1,   -8,
        -1,  0,  0,   95,         1,  0, -1,   46,
        -1,  0,  0,   62,         1,  0, -1,   77,
        -1,  0,  0,   54,         1,  0,  1,   57,
        -1,  0,  0,   56,         1,  0,  1,   89,
        -1,  0,  0,   48,         1,  0,  1,  103,
        -1,  0,  0,   70,         1,  0,  1,  129,
        -1,  0,  0,   94,         1,  0,  1,  139,
        -1,  0,  0,   42,         1,  0,  1,  128,
        -1,  2,  0,  116,         1,  0,  1,   89,
        -1,  2,  0,  105,         1,  0,  1,   86,
        -1,  2,  0,   91,         1,  0,  3,  140,
        -1,  2,  0,   94,         1,  0,  3,  133,
        -1,  2,  0,  130,         1,  0,  3,  142,
        -1,  2,  0,   79,         1,  0,  3,  118,
        -1,  2,  0,  120,         1,  0,  3,  137,
        -1,  2,  0,  124,         1,  0,  3,   84,
        -1,  2,  0,   -8,         1,  0,  3,  101)
  xx    <- matrix(z,ncol=4, byrow=TRUE)
  dimnames(xx) <- list(NULL,c("z2","xS","xT","y"))
  z2    <- xx[,"z2"]; xS <- xx[,"xS"]; xT <- xx[,"xT"]
  x     <- cbind(1, z2, xS+xT, xS-xT, xS^2+xT^2, xS^2-xT^2, xT^3)
  y     <- xx[,"y"]
  z     <- dfrpar(x, "huber",psipar=1.345)
#
#  Tau-test  and  shift estimate
#
{ 
  cat("Results (linearity test)\n")
  np    <- 7;   nq <- 4   # Test linearity
  z     <- tautest(x,y,np,nq)
  cat("Results (parallelism test)\n")
  np    <- 4;   nq <- 3  # Test parallelism
  z     <- tautest(x,y,np,nq)
  z     <- dshift(x, z$thetas, z$sigma, z$rs, nq)
}
#------------------------------------------------------------------------
# Input data; set defaults
# 
  z <- c(35.3,  20,  10.98,
         29.7,  20,  11.13,
         30.8,  23,  12.51,
         58.8,  20,   8.40,
         61.4,  21,   9.27,
         71.3,  22,   8.73,
         74.4,  11,   6.36,
         76.7,  23,   8.50,
         70.7,  21,   7.82,
         57.5,  20,   9.14,
         46.4,  20,   8.24,
         28.9,  21,  12.19,
         28.1,  21,  11.88,
         39.1,  19,   9.57,
         46.8,  23,  10.94,
         48.5,  20,   9.58,
         59.3,  22,  10.09,
         70.0,  22,   8.11,
         70.0,  11,   6.83,
         74.5,  23,   8.88,
         72.1,  20,   7.68,
         58.1,  21,   8.47,
         44.6,  20,   8.86,
         33.4,  20,  10.36,
         28.6,  22,  11.08)
 x      <- matrix(z, ncol=3, byrow=TRUE)
 y      <- x[,3]; x[,2:3] <- x[,1:2]; x[,1] <- 1
 n      <- length(y); np <- ncol(x); nq <- np - 1
#
# Optimal tau-test based on Schweppe-type estimates
#
 z      <- tauare(itype=3,mu=1,cpsi=2.665,bb=0,sigmax=1)
 dfrpar(x, "Sch-Tau",upar=2.67); .dFvPut(1,"isg"); 
 .dFv   <- .dFvGet(); dfcomn(d=.dFv$ccc)
# Full model: initial estimates of theta, sigma and weights
 dfcomn(xk=np)  # Needed for userfd 
 zr     <- rbmost(x,y,cc=1.5)
 theta0 <- zr$theta; sigma0 <- zr$sigma; nitw0 <- zr$nitw 
#
# Initial and final values of weights 
#
 z      <- wimedv(x)
 z      <- wyfalg(x, z$a, zr$g, nvarq=nq, igwt=1)
 wgt    <- 1/z$dist ; wgt[wgt>1.e6] <- 1.e6
# Full model: covariance matrix of coefficients and inverse
 z      <- kiedch(wgt)
 zc     <- ktaskw(x, z$d, z$e, f=1/n, iainv=1)
 cov    <- zc$cov; ainv <- zc$ainv
# Full model: Final estimate of theta and sigma
 ribeth(wgt)
 zf     <- rywalg(x, y,theta0,wgt,cov, sigmai=sigma0)
 thetaf <- zf$theta[1:np]; sigma <- zf$sigmaf; nitf <- zf$nit
# Small model: Final estimate of theta and sigma
 covi   <- cov[1:(nq*(nq+1)/2)]
 xt     <- x[,1:nq,drop=FALSE]
 zs     <- rywalg(xt, y, theta0, wgt, covi, sigmai=sigma, isigma=0)
 thetas <- zs$theta[1:nq]; nits <- zs$nit
# Compute Tau-test statistic
 ft     <- tftaut(zf$rs,zs$rs,wgt,rho,np,nq,sigma)
 ftau   <- ft$ftau
# P-value
 z      <- ttaskt(cov, ainv, np, nq, fact=n)
 z      <- tteign(z$covtau,nq)
 xlmbda <- z$xlmbda[1:(np-nq)]
 mult   <- rep(1, length=np)
 delta  <- rep(0, length=np)
 z      <- ruben(xlmbda, delta, mult,ftau, xmode=-1, maxit=100, eps=0.0001)
 P      <- 1-z$cumdf
#.......................................................................
{
 cat(" Optimal Tau-test : Schweppe-type estimates\n")
 cat(" theta0: ",round(theta0[1:np],3),"\n sigma0, nitw: ")
 cat(round(c(sigma0,nitw0),3),sep=c(", ","\n"))
 cat(" thetaf: ",round(thetaf,3),"\n sigma, nit: ")
 cat(round(c(sigma,nitf),3),sep=c(", ","\n"))
 cat(" thetas: ",round(thetas,3),"\n sigma, nit: ")
 cat(round(c(sigma,nits),3),sep=c(", ","\n"))
 cat(" F_tau =",round(ftau,3),", P =",P,"\n")
}
#=======================================================================
 rn2mal <- function(x,y,b2,c,nq) {
 n <- length(y); np <- ncol(x)
#
#  Rn2-test on Mallows estimators 
#  ==============================
 dfrpar(x, "mal-std", b2, c)
 .dFvPut(1,"isg"); .dFv <- .dFvGet(); dfcomn(d=.dFv$ccc)
#
# Initial and final values of weights
#
 z     <- wimedv(x)
 z     <- wyfalg(x, z$a, wgt)
 wgt   <- Www(z$dist); nitw <- z$nit
#
# Initial theta and sigma (using weighted LAR)
#
 ribet0(wgt, isqw=0)
 xt    <- x*wgt
 yt    <- y * wgt
 z     <- rilars(xt, yt)
 theta0 <- z$theta; sigma0 <- z$sigma
#
# Initial value of COV
#
 z     <- kiedch(wgt)
 zc    <- ktaskw(x, z$d, z$e, f=1/n)
 covi  <- zc$cov 
#
# Solution by means of RYWALG. 
#
 z     <- ribeth(wgt)
 beta  <- z$bta
 zw    <- rywalg(x, y, theta0, wgt, covi, sigmai=sigma0)
 theta1 <- zw$theta[1:np]; sigma1 <- zw$sigmaf; nit1 <- zw$nit
#
# Unscaled covariance matrix of coefficients
#
  zc   <- kfedcb(wgt, zw$rs, sigma=sigma1)
  z    <- ktaskw(x, zc$d, zc$e, f=1/n)
  cov1 <- z$cov
#
# Rn2-test statistic and significance
#
 z     <- tfrn2t(cov1,theta1,n,nq)
 rn2m  <- z$rn2t/(n*sigma1^2)
 z     <- chisq(1,np-nq,rn2m)
 p1    <- 1.-z$p
 list(theta1=theta1, sigma1=sigma1, wgt=wgt, nitw=nitw, nit1=nit1,
      rn2m=rn2m, p1=p1)}
#------------------------------------------------------------------------
#
# Read data
# 
  z <- c(35.3,  20,  10.98,
         29.7,  20,  11.13,
         30.8,  23,  12.51,
         58.8,  20,   8.40,
         61.4,  21,   9.27,
         71.3,  22,   8.73,
         74.4,  11,   6.36,
         76.7,  23,   8.50,
         70.7,  21,   7.82,
         57.5,  20,   9.14,
         46.4,  20,   8.24,
         28.9,  21,  12.19,
         28.1,  21,  11.88,
         39.1,  19,   9.57,
         46.8,  23,  10.94,
         48.5,  20,   9.58,
         59.3,  22,  10.09,
         70.0,  22,   8.11,
         70.0,  11,   6.83,
         74.5,  23,   8.88,
         72.1,  20,   7.68,
         58.1,  21,   8.47,
         44.6,  20,   8.86,
         33.4,  20,  10.36,
         28.6,  22,  11.08)
  x      <- matrix(z, ncol=3, byrow=TRUE)
  y      <- x[,3]; x[,2:3] <- x[,1:2];  x[,1] <- 1
  n      <- length(y); np <- ncol(x); nq <- np - 1
  wgt    <- vector("numeric",length(y))
  z      <- rn2mal(x, y, 4, 1.5, nq)
#.......................................................................
{
 cat("Rn2-test on Mallows estimators\n")
 cat(" theta1: ",round(z$theta1,3),"\n sigma1, nitw, nit1: ")
 cat(round(c(z$sigma1,z$nitw,z$nit1),3),sep=c(", ",", ","\n"))
 cat(" Rn2 =",round(z$rn2m,3),", P =",z$p1,"\n")
}


#
# ---- Examples of Chapter 7: Breakdown point regression ------
#

#
# Read data; load defaults
# 
  z <- c(80, 27, 89, 42, 
         80, 27, 88, 37, 
         75, 25, 90, 37, 
         62, 24, 87, 28,
         62, 22, 87, 18, 
         62, 23, 87, 18, 
         62, 24, 93, 19, 
         62, 24, 93, 20,
         58, 23, 87, 15, 
         58, 18, 80, 14, 
         58, 18, 89, 14, 
         58, 17, 88, 13,
         58, 18, 82, 11, 
         58, 19, 93, 12, 
         50, 18, 89,  8, 
         50, 18, 86,  7,
         50, 19, 72,  8, 
         50, 19, 79,  8, 
         50, 20, 80,  9, 
         56, 20, 82, 15,
         70, 20, 91, 15)
 x       <- matrix(z, ncol=4, byrow=TRUE)
 y       <- x[,4]; x[,4] <- 1
 n       <- length(y); np <- ncol(x)
 nq      <- np+1
 dfvals()
#
# Least median of squares
#
  zr     <- hylmse(x,y, nq, ik=1, iopt=3, intch=1)
  theta1 <- zr$theta; xmin1 <- zr$xmin
  zr     <- hylmse(x,y, nq, ik=2, iopt=3, intch=1)
  theta2 <- zr$theta; xmin2 <- zr$xmin
  zr     <- hylmse(x,y, nq, ik=1, iopt=1, intch=1)
  theta3 <- zr$theta; xmin3 <- zr$xmin

#
# Least trimmed squares
#
  zr     <- hyltse(x,y, nq, ik=1, iopt=3, intch=1)
  theta4 <- zr$theta; xmin4 <- zr$smin
  zr     <- hyltse(x,y, nq, ik=2, iopt=3, intch=1)
  theta5 <- zr$theta; xmin5 <- zr$smin
  zr     <- hyltse(x,y, nq, ik=1, iopt=1, intch=1)
  theta6 <- zr$theta; xmin6 <- zr$smin

#
# S-estimate
#
  z      <- dfrpar(x,'S')
  z      <- ribetu(y) 
  zr     <- hysest(x,y, nq, iopt=3, intch=1)
  theta7 <- zr$theta[1:np]; xmin7 <- zr$smin
  zr     <- hysest(x,y, nq, iopt=1, intch=1)
  theta8 <- zr$theta[1:np]; xmin8 <- zr$smin
#.......................................................................
{
  cat("Results\n theta1 = (")
  cat(round(theta1,3),sep=", ") 
  cat("), xmin1 ="); cat(round(xmin1,3))
  cat("\n theta2 = ("); cat(round(theta2,3),sep=", ") 
  cat("), xmin2 ="); cat(round(xmin2,3))
  cat("\n theta3 = ("); cat(round(theta3,3),sep=", ") 
  cat("), xmin3 ="); cat(round(xmin3,3))
  cat("\n theta4 = ("); cat(round(theta4,3),sep=", ") 
  cat("), xmin4 ="); cat(round(xmin4,3))
  cat("\n theta5 = ("); cat(round(theta5,3),sep=", ") 
  cat("), xmin5 ="); cat(round(xmin5,3))
  cat("\n theta6 = ("); cat(round(theta6,3),sep=", ") 
  cat("), xmin6 ="); cat(round(xmin6,3))
  cat("\n theta7 = ("); cat(round(theta7,3),sep=", ") 
  cat("), xmin7 ="); cat(round(xmin7,3))
  cat("\n theta8 = ("); cat(round(theta8,3),sep=", ") 
  cat("), xmin8 ="); cat(round(xmin8,3),"\n")
}

#
# ---- Examples of Chapter 8: M-estimates of covariance matrices ------
#

#
# Read data; set defaults
# 
  z <- c(4.37, 5.23,   4.38, 5.02,
         4.56, 5.74,   4.42, 4.66,
         4.26, 4.93,   4.29, 4.66,
         4.56, 5.74,   4.38, 4.90,
         4.30, 5.19,   4.22, 4.39,
         4.46, 5.46,   3.48, 6.05,
         3.84, 4.65,   4.38, 4.42,
         4.57, 5.27,   4.56, 5.10,
         4.26, 5.57,   4.45, 5.22,
         4.37, 5.12,   3.49, 6.29,
         3.49, 5.73,   4.23, 4.34,
         4.43, 5.45,   4.62, 5.62,
         4.48, 5.42,   4.53, 5.10,
         4.01, 4.05,   4.45, 5.22,
         4.29, 4.26,   4.53, 5.18,
         4.42, 4.58,   4.43, 5.57,
         4.23, 3.94,   4.38, 4.62,
         4.42, 4.18,   4.45, 5.06,
         4.23, 4.18,   4.50, 5.34,
         3.49, 5.89,   4.45, 5.34,
         4.29, 4.38,   4.55, 5.54,
         4.29, 4.22,   4.45, 4.98,
         4.42, 4.42,   4.42, 4.50,
         4.49, 4.85)
 cx      <- matrix(z, ncol=2, byrow=TRUE)
 n       <- nrow(cx); np <- ncol(cx)
 dst0    <- vector("numeric",n)
#-----------------------------------------------------------------------
# Classical covariance
#
  t0     <- apply(cx, 2, mean)
  xmb    <- sweep(cx, 2, t0)
  cv0    <- crossprod(xmb)/n
# Mahalanobis distances
  cvm1   <- solve(cv0)
  for (i in 1:n) {
      z  <- xmb[i,,drop=FALSE]; dst0[i] <- sqrt(z %*% cvm1 %*% t(z))}

#=======================================================================
# M-estimate of covariance
#
   zc    <- cicloc()
   za    <- cia2b2(nvar=np)
   a2    <- za$a2; b2 <- za$b2
   zd    <- cibeat(a2, b2, np)
   cw    <- zc$c;  dv <- zd$d
   dfcomn(iucv=1, a2=a2, b2=b2, bt=dv, cw=cw)
#  zf    <- cifact(a2,b2,np);  fc <- zf$fc
   z     <- cimedv(cx)
   ai    <- z$a; ti <- z$t; fc <- 1
#-----------------------------------------------------------------------
# With prescription F0
   zd    <- cyfalg(cx,ai,ti)
   zc    <- cfrcov(zd$a,np,fc)
   cv1   <- zc$cov; t1 <- zd$t; dst1 <- zd$dist; nt1 <- zd$nit
#-----------------------------------------------------------------------
# With prescription NH
   zd    <- cynalg(cx,ai,ti)
   zc    <- cfrcov(zd$a,np,fc)
   cv2   <- zc$cov; t2 <- zd$t; dst2 <- zd$dist; nt2 <- zd$nit
#-----------------------------------------------------------------------
# With prescription CG
   zd    <- cygalg(cx,ai,ti)
   zc    <- cfrcov(zd$a,np,fc)
   cv3   <- zc$cov; t3 <- zd$t; dst3 <- zd$dist; nt3 <- zd$nit
#.......................................................................
{
   cat("Results\n\n cv0[1,1],cv0[2,1],cv0[2,2] = (")
   cat(round(as.vector(cv0)[-2],3),sep=", ")
   cat(")\n t0 = ("); cat(round(t0,3),sep=", ")
   cat(")\n dist0 :\n ")
   cat(round(dst0,3),sep=c(rep(", ",9),",\n "))
   cat("\n cv1[1,1],cv1[2,1],cv1[2,2] = (")
   cat(round(cv1,3),sep=", ")
   cat(")\n t1 = ("); cat(round(t1,3),sep=", ") 
   cat("), nit1 =",nt1); cat("\n dist1 :\n ")
   cat(round(dst1,3),sep=c(rep(", ",9),",\n "))
   cat("\n cv2[1,1],cv2[2,1],cv2[2,2] = (")
   cat(round(cv2,3),sep=", ")
   cat(")\n t2 = ("); cat(round(t2,3),sep=", ") 
   cat("), nit2 =",nt2); cat("\n dist2 :\n ")
   cat(round(dst2,3),sep=c(rep(", ",9),",\n "))
   cat("\n cv3[1,1],cv3[2,1],cv3[2,2] = (")
   cat(round(cv3,3),sep=", ")
   cat(")\n t3 = ("); cat(round(t3,3),sep=", ") 
   cat("), nit3 =",nt3); cat("\n dist3 :\n ")
   cat(round(dst3,3),sep=c(rep(", ",9),",\n "))
}


#
# ----------- Examples of Chapter 9: Mixed procedures --------------
#


 bindec <- function(np,ind,cpc,cpr) {
 n      <- length(ind)
 ccar   <- matrix("-",ncol=np, nrow=n)
 for (i in 1:n) {
    j   <- 0
    num <- abs(ind[i])
    while (num != 0 & j < np) {
     j   <- j+1
     if (num %% 2 == 1) ccar[i,j] <- "X"
     num <- num %/% 2}}
   data.frame(Cp=round(cpc,3),Cp.r=round(cpr,3),ipr=ind,i=ccar)
 }
#-----------------------------------------------------------------------
# Read data
# 
 z <- c(-1, -2,  0,   35,         1,  0, -3,   20,
        -1, -2,  0,   30,         1,  0, -3,   39,
        -1, -2,  0,   24,         1,  0, -3,   16,
        -1, -2,  0,   37,         1,  0, -3,   27,
        -1, -2,  0,   28,         1,  0, -3,  -12,
        -1, -2,  0,   73,         1,  0, -3,    2,
        -1, -2,  0,   31,         1,  0, -3,   31,
        -1, -2,  0,   21,         1,  0, -1,   26,
        -1, -2,  0,   -5,         1,  0, -1,   60,
        -1,  0,  0,   62,         1,  0, -1,   48,
        -1,  0,  0,   67,         1,  0, -1,   -8,
        -1,  0,  0,   95,         1,  0, -1,   46,
        -1,  0,  0,   62,         1,  0, -1,   77,
        -1,  0,  0,   54,         1,  0,  1,   57,
        -1,  0,  0,   56,         1,  0,  1,   89,
        -1,  0,  0,   48,         1,  0,  1,  103,
        -1,  0,  0,   70,         1,  0,  1,  129,
        -1,  0,  0,   94,         1,  0,  1,  139,
        -1,  0,  0,   42,         1,  0,  1,  128,
        -1,  2,  0,  116,         1,  0,  1,   89,
        -1,  2,  0,  105,         1,  0,  1,   86,
        -1,  2,  0,   91,         1,  0,  3,  140,
        -1,  2,  0,   94,         1,  0,  3,  133,
        -1,  2,  0,  130,         1,  0,  3,  142,
        -1,  2,  0,   79,         1,  0,  3,  118,
        -1,  2,  0,  120,         1,  0,  3,  137,
        -1,  2,  0,  124,         1,  0,  3,   84,
        -1,  2,  0,   -8,         1,  0,  3,  101)
  xx    <- matrix(z,ncol=4, byrow=TRUE)
  dimnames(xx) <- list(NULL,c("z2","xS","xT","y"))
  z2    <- xx[,"z2"]; xS <- xx[,"xS"]; xT <- xx[,"xT"]
  x     <- cbind(1, z2, xS+xT, xS-xT, xS^2+xT^2, xS^2-xT^2, xT^3)
  y     <- xx[,"y"]
  wgt   <- vector("numeric",length(y))
  n     <- 56; np <- 7
 dfvals()
# Compute classical sigma and the t-statistics
 dfrpar(x,"ols",-1,-1); .dFv   <- .dFvGet()
 z     <- mirtsr(x,y,.dFv$ite)
 sigmc <- z$sigma; tstac <- z$t
 
# Compute robust sigma and the t-statistics
 dfrpar(x,"huber",-1,-1); .dFv   <- .dFvGet()
 z     <- mirtsr(x,y,.dFv$ite)
 sigmr <- z$sigma; tstar <- z$t
#
# All possible regressions including  the constant and linear terms
#
 vp     <- rep(-0.5, length=np)
 vp[1]  <- 3; vp[3]  <- 2; vp[4]  <- 1
 za     <- mfragr(x, y, vp, nc=18, .dFv$ite, sigmac=sigmc, sigmar=sigmr)
#
# Priorites by means of t-directed search
#
 zt     <- mfragr(x, y, tstar, nc=7, .dFv$ite, sigmac=sigmc, sigmar=sigmr)
#.......................................................................
{
 cat(" Estimates of sigma\n ")
 cat(" sigmc =",round(sigmc,3),", sigmr =",round(sigmr,3),"\n")
 cat(" Regressions on subset of variables:\n")
 cat("  C{p} C{p,@} ipr 1 2 3 4 5 6 7\n")
 cat(t(bindec(np,za$ipr,za$cpc,za$cpr)),sep=c(rep(" ",9),"\n"))
 cat("\n t-directed search\n")
 cat(" tstar[1:7]=(", round(tstar,3),sep=c("",rep(", ",6)))
 cat(")\n   C_p C{p,@} ipr 1 2 3 4 5 6 7\n")
 cat(t(bindec(np,zt$ipr,zt$cpc,zt$cpr)),sep=c(rep(" ",9),"\n")) 
}
#=======================================================================
#
# Read data; set defaults
# 
  z <- c(4.37, 5.23,   4.48, 5.42,   4.38, 5.02,   4.53, 5.10,
         4.56, 5.74,   4.01, 4.05,   4.42, 4.66,   4.45, 5.22,
         4.26, 4.93,   4.29, 4.26,   4.29, 4.66,   4.53, 5.18,
         4.56, 5.74,   4.42, 4.58,   4.38, 4.90,   4.43, 5.57,
         4.30, 5.19,   4.23, 3.94,   4.22, 4.39,   4.38, 4.62,
         4.46, 5.46,   4.42, 4.18,   3.48, 6.05,   4.45, 5.06,
         3.84, 4.65,   4.23, 4.18,   4.38, 4.42,   4.50, 5.34,
         4.57, 5.27,   3.49, 5.89,   4.56, 5.10,   4.45, 5.34,
         4.26, 5.57,   4.29, 4.38,   4.45, 5.22,   4.55, 5.54,
         4.37, 5.12,   4.29, 4.22,   3.49, 6.29,   4.45, 4.98,
         3.49, 5.73,   4.42, 4.42,   4.23, 4.34,   4.42, 4.50,
         4.43, 5.45,   4.49, 4.85,   4.62, 5.62)
 cx      <- matrix(z, ncol=2, byrow=TRUE)
 n       <- nrow(cx); np <- ncol(cx)
 y       <- vector("numeric",length=n)
#
# Minimum Volume Ellipsoid covariances 
#
 dfvals(); .dFv   <- .dFvGet()
 z       <- mymvlm(cx,y,ilms=0,iopt=3,iseed=5321)
 dst     <- z$d;  cv <- z$cov; xvol <- z$xvol
#.......................................................................
{
 cat("Minimum Volume Ellipsoid covariances\n cv = (")
 cat(round(cv,3),sep=c(", ",", "))
 cat("), Objective function value =",round(xvol,3),"\ndistances:\n")
 cat(round(dst,3),sep=c(rep(", ",9),",\n"))
}
#=======================================================================  
#
# Read data; load defaults
# 
  z <- c(80, 27, 89, 42, 
         80, 27, 88, 37, 
         75, 25, 90, 37, 
         62, 24, 87, 28,
         62, 22, 87, 18, 
         62, 23, 87, 18, 
         62, 24, 93, 19, 
         62, 24, 93, 20,
         58, 23, 87, 15, 
         58, 18, 80, 14, 
         58, 18, 89, 14, 
         58, 17, 88, 13,
         58, 18, 82, 11, 
         58, 19, 93, 12, 
         50, 18, 89,  8, 
         50, 18, 86,  7,
         50, 19, 72,  8, 
         50, 19, 79,  8, 
         50, 20, 80,  9, 
         56, 20, 82, 15,
         70, 20, 91, 15)
 x       <- matrix(z, ncol=4, byrow=TRUE)
 y       <- x[,4]; x[,4] <- 1
 n       <- length(y); np <- ncol(x)
 nq      <- np+1
 dfvals()
#
# High breakdown point & high efficiency regression
#
 dfrpar(x,"S",-1,-1)
 z <- myhbhe(x, y, iseed=5431)
#.......................................................................
{
 cat("High breakdown point & high efficiency regression\n")
 cat(" theta0 = ("); cat(round(z$theta0,3),sep=", ")
 cat("), sigma0 =",round(z$sigm0,3))
 cat("\n theta1 = ("); cat(round(z$theta1,3),sep=", ")
 cat("), sigma1 = ",round(z$sigm1,3),", tbias =",sep="")
 cat(round(z$tbias,3),"\n")
}


#
# -------- Examples of Chapter 10: M-estimates for discrete GLM ---------
#

 glmb <- function(x,y,n,np,upar) {
#
# BI estimates of theta, A, ci and wa: Bernouilli responses, b=upar
#
# Initial theta, A (A0) and c (c0)
#
 ni     <- rep.int(1,n)
 z      <- gintac(x,y,ni,icase=1,b=upar,c=1.5)
 theta0 <- z$theta[1:np]; A0 <- z$a; c0 <- z$ci
# Initial distances |Ax_i| and cut off points a_i (wa)
 wa     <- upar/z$dist  
 vtheta <- x %*% theta0
 z      <- gfedca(vtheta, c0, wa, ni, icase=1)
 zc     <- ktaskw(x, z$d, z$e, f=1/n)      # See Chpt. 4
 covi   <- zc$cov
# Final theta, A, c (ci) and a (wa)
 z      <- gymain(x, y, ni, covi, A0, theta0, b = upar) 
 theta  <- z$theta; A <- z$a; ci <- z$ci; wa <- z$wa; nit <- z$nit
# Final cov. matrix and std. dev's of coeff. estimates
 z      <- gfedca(z$vtheta, ci, wa, ni, icase=1)
 sdev   <- NULL
 zc     <- ktaskw(x, z$d, z$e, f=1/n)
 for (i in 1:np) {ii <- i*(i+1)/2; sdev <- c(sdev,zc$cov[ii])}
 sdev   <- sqrt(sdev)
 list(theta=theta, A=A, ci=ci, wa=wa, nit=nit, sdev=sdev)}
#-----------------------------------------------------------------------
# Read data; load defaults
# 
  z <- c(3.70, 0.825, 1,   3.50, 1.090, 1,
         1.25, 2.500, 1,   0.75, 1.500, 1,
         0.80, 3.200, 1,   0.70, 3.500, 1,
         0.60, 0.750, 0,   1.10, 1.700, 0,
         0.90, 0.750, 0,   0.90, 0.450, 0,
         0.80, 0.570, 0,   0.55, 2.750, 0,
         0.60, 3.000, 0,   1.40, 2.330, 1,
         0.75, 3.750, 1,   2.30, 1.640, 1,
         3.20, 1.600, 1,   0.85, 1.415, 1,
         1.70, 1.060, 0,   1.80, 1.800, 1,
         0.40, 2.000, 0,   0.95, 1.360, 0,
         1.35, 1.350, 0,   1.50, 1.360, 0,
         1.60, 1.780, 1,   0.60, 1.500, 0,
         1.80, 1.500, 1,   0.95, 1.900, 0,
         1.90, 0.950, 1,   1.60, 0.400, 0,
         2.70, 0.750, 1,   2.35, 0.300, 0,
         1.10, 1.830, 0,   1.10, 2.200, 1,
         1.20, 2.000, 1,   0.80, 3.330, 1,
         0.95, 1.900, 0,   0.75, 1.900, 0,
         1.30, 1.625, 1)
 x     <- matrix(z, ncol=3, byrow=TRUE)
 y     <- x[,3]; x[,3] <- log(x[,2]); x[,2] <- log(x[,1]) ; x[,1] <- 1
 n     <- length(y); np <- ncol(x)
 dfvals()
 upar  <- 3.2*sqrt(np)
 z1    <- glmb(x,y,n,np,upar)
 
 upar  <- 3.7*sqrt(np)
 z2    <- glmb(x,y,n,np,upar)

 z     <- glmb(x,y,n,np,300) # Classical estimates
#.......................................................................
{
 cat("\n Robust estimates : upar=5.5426, nit =",z1$nit,"\n")
 cat(" {theta[i] (sdev[i]), i=1:3}\n ")
 for (i in 1:3) cat(round(z1$theta[i],3)," (",round(z1$sdev[i],3),")  ",sep="")
 cat("\n\n Robust estimates : upar=6.4086, nit =",z2$nit,"\n")
 cat(" {theta[i] (sdev[i]), i=1:3}\n ")
 for (i in 1:3) cat(round(z2$theta[i],3)," (",round(z2$sdev[i],3),")  ",sep="")
 cat("\n\n Classical estimates : upar=300, nit =",z$nit,"\n")
 cat(" {theta[i] (sdev[i]), i=1:3}\n ")
 for (i in 1:3) cat(round(z$theta[i],3)," (",round(z$sdev[i],3),")  ",sep="")
 cat("\n")
}
#-----------------------------------------------------------------------

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