* remove all cases with missing values before running this.
* make sure that the filter index is filter_$.

if you run more than once delete filterab.
GET
  FILE='C:\good.sav'.


volume  filter_$ zwater80 to zpeop81.

set mxloop 9999.

Define volume(!POSITIONAL !TOKENS(1) /!POSITIONAL !CMDEND).
SORT CASES BY
  !1 .

AUTORECODE
  VARIABLES=!1  /INTO filterab.
compute filterab = filterab -1.

Matrix.

get bigx /varaibles = !2 / missing = omit.
get ind /varaibles = filterab / missing = omit.

compute nr = nrow(bigx).
compute j = make(nr,1,1).
compute n1e = t(j)*ind.
compute n1p = nr-n1e.
compute nc =ncol(bigx).

* print bigx.

print n1e.
print n1p.
print nr.

compute xe = make(n1e,nc,0).
compute xp = make(n1p,nc,0).

loop i = 1 to n1e.
loop j = 1 to nc.
compute xe(i,j) = bigx(i+n1p,  j).
end loop.
end loop.


loop i = 1 to n1p.
loop j = 1 to nc.
compute xp(i,j) = bigx(i,j).
end loop.
end loop.


compute d1 = det(T(xe)*xe/n1e).
compute d2 = det(T(xp)*xp/n1p).
compute vol = (d1/d2)**(1/(nc+1)).

print vol.


end matrix.

!enddefine.