[R] Iterative loop using "repeat"

mary mary.dama at libero.it
Sat Jan 5 12:32:39 CET 2013


Thanks for the help:your reply has focused my problem

in particular I'm trying to do a converge process; 

the robustm() function is: 
function (x,z)           
1#  {eigen<-eigen(x) 
2# d<-madmatrix(z)                                                                
##I have created this function to calculate "mad" of a whole matrix 
3# eigenc<-eigen$vectors 
4# q<-d%*%eigenc 
5# invQ<-matrix.inverse(q) 
6# sZ<-mdefpos(z,invQ)                                     ##this function
serves me to define positive my new matrix Z, it's  X%*%invQ 
7# madZ<-madmatrix(sZ) 
8# S_X<-q%*%(madsZ)^2%*%t(q) 
return(S_X) 
} 

 reviewing this function I realized that it can not be applied in an
iterative manner in the next step because every time a new matrix z should
be fed back into the process and then calculate a new scatter matrix; in the
code above : 
(x) is a scatter matrix, Z is a matrix (n*p) of original data that I have
used to obtain a scatter matrix... 
in line 6# I need this new matrix sZ because it will be my new (z) if I
reiterate the process on the new scatter matrix S_X, in fact my function
robustm() ask me the scatter matrix and the data matrix so... 
how I can do this...and the reiterate the process so that the matrix
converges?? 




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