In this calculation:
(dg0%*%t(dx0))
 is

    [,1]  [,2]
[1,]    0 -0.75
[2,]    0  0.50

So: exp2 = NaN

It is extremely easy to find out the issue if you go back line by line,
this is a basic procedure of debugging. Please do it yourself next time.




On Mon, Jan 13, 2014 at 3:09 PM, IZHAK shabsogh <ishaqbaba@yahoo.com> wrote:

> kindly help me fine what is the mistake with following:
> my aim is to compute those steps and obtain a vector with values (3,5)
> but i am geting (NAN,NAN)
>
> Q<-matrix(c(5,-3,-3,2),2,2)
> b<-rbind(0,1)
> H0<-diag(2)
> x0<-rbind(0,0)
> d0<-b
> g0<--b
> a0<--(t(g0)%*%d0)/(t(d0)%*%Q%*%d0)
> x1<-x0+a0[,1]*d0
> dx0<-x1-x0
> g1<-Q%*%x1-b
> dg0<-g1-g0
> exp1<-(t(dg0)%*%H0%*%dg0)/(t(dg0)%*%dx0)
> exp2<-(dx0%*%t(dx0))/(dg0%*%t(dx0))
> exp3<-(dx0%*%t(dg0)%*%H0 +H0%*%dg0%*%t(dx0))/(dx0%*%t(dg0))
> H1<-H0+(1+exp1[,1])*exp2-exp3
> d1<--H1%*%g1
> a2<-(t(g1)%*%d1)/(t(d1)%*%Q%*%d1)
> x2<-x1+a2[,1]*d1
>
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