Subroutine regression(n,p,y)!
!***************************************************************
! A routine to calculate the regression coefficients from a 
!datamatrix specified in the calling program and held in a 
!module called test.  The matrix is of dimensions n, p and the
!response vector is y.  This routine uses the standardized correlaion
!matrices to calulate b (which also must be specified in the calling
!program and held in test.
!			Version 2/1/02        DH
!****************************************************************

USE DFIMSLSS
USE IMSLf90
use test 
implicit none

integer, intent(in) :: n,p
real, intent(in) :: y(n,1) 
real :: temp(n,1),X(n,p),bnew(p,1)
real :: xt(p,n),zX(n,p),zy(n,1)
real :: C(p,p),r(p,1),Cinv(p,p)
real :: avg,var,vary
integer :: i,j,k


X=Xhat

!standardize the data
do i=1,p  
	call average(n,X(:,i),avg)
	call varience(n,X(:,i),var)
	do j=1,n
		zX(j,i)=(X(j,i)-avg)/sqrt(var)
	end do
enddo
call average(n,y,avg)
call varience(n,y,var)
do j=1,n
	zy(j,1)=(y(j,1)-avg)/sqrt(var)
end do

do i=1,p
	do j=1,p
		call correlation(n,zX(:,i),zX(:,j),C(i,j))
	end do
	call correlation(n,zy,zX(:,i),r(i,1))
!write(4,'(<p>(f7.2,1x))') (C(i,j),j=1,p)
end do

Cinv = .i. C
bnew = Cinv .x. r

! now put betas back into non-standardized form!
call varience(n,y,vary)
do i=1,p
	call varience(n,X(:,i),var)
	b(i,1)=bnew(i,1)*(sqrt(vary)/sqrt(var))
end do


return
end subroutine regression