c	***********************************************************************
	subroutine intersp(yy,zz,m,y,z,n,opt)
c	interpolation soubroutine. input values: y(n) at z(n). 
c	output values: yy(m) at zz(m). options: 1 -> lineal; 2 -> logarithmic

c       jul 2011 malv+fgg
c	***********************************************************************

	implicit none

	integer	n,m,i,j,opt
	real	zz(m),yy(m),z(n),y(n)
	real	zmin,zzmin,zmax,zzmax

!	write(*,*) ' interpolating'
	call minsp(z,n,zmin)
	call minsp(zz,m,zzmin)
	call maxsp(z,n,zmax)
	call maxsp(zz,m,zzmax)

	if(zzmin.lt.zmin)then
	  write(*,*) 'from interp: new variable out of limits'
	  write(*,*) zzmin,'must be .ge. ',zmin
	  stop
!	elseif(zzmax.gt.zmax)then
!	  write(*,*)'from interp: new variable out of limits'
!	  write(*,*)zzmax, 'must be .le. ',zmax
!	  stop
	end if

	do 1,i=1,m

	do 2,j=1,n-1
	if(zz(i).ge.z(j).and.zz(i).lt.z(j+1)) goto 3
 2	continue
c	in this case (zz(m).ge.z(n)) and j leaves the loop with j=n-1+1=n
	if(opt.eq.1)then
	  yy(i)=y(n-1)+(y(n)-y(n-1))*(zz(i)-z(n-1))/(z(n)-z(n-1))
	elseif(opt.eq.2)then
	  if(y(n).eq.0.0.or.y(n-1).eq.0.0)then
		yy(i)=0.0
	  else
		yy(i)=exp(log(y(n-1))+log(y(n)/y(n-1))*
     @		(zz(i)-z(n-1))/(z(n)-z(n-1)))
	  end if
	else
	  write(*,*)' from interp error: opt must be 1 or 2, opt= ',opt
	end if
	goto 1
 3	continue
	if(opt.eq.1)then
	  yy(i)=y(j)+(y(j+1)-y(j))*(zz(i)-z(j))/(z(j+1)-z(j))
	elseif(opt.eq.2)then
	  if(y(j+1).eq.0.0.or.y(j).eq.0.0)then
		yy(i)=0.0
	  else
		yy(i)=exp(log(y(j))+log(y(j+1)/y(j))*
     @		(zz(i)-z(j))/(z(j+1)-z(j)))
	  end if
	else
	  write(*,*)' from interp error: opt must be 1 or 2, opt= ',opt
	end if
 1	continue

	return
	end