!subroutine measure_ft is where we do some tests to see if the matrix is sensible

subroutine measure_ft(M, det, tune)
use bmad
implicit none
real(rp), allocatable:: M(:,:)
real(rp) tune(3)
real(rp) det
real(rp) half_trace
integer n,i
integer j

n=size(M,1)

print *
print *,' n= ', n
print *,'M'
do i=1,n
 print '(6es12.4)',(M(i,j),j=1,n)
end do

 tune = 0.
do i = 1,n/2
 half_trace =  (M(2*i-1,2*i-1)+M(2*i,2*i))/2
 if(abs(half_trace) <= 1. )tune(i) = acos(half_trace)/twopi
 if(abs(half_trace) > 1. )tune(i) = -acosh(half_trace)/twopi
end do
det  = determinant(M(1:n,1:n))
tune(1:2) = 1.-tune(1:2)
print '(a,es12.4)',' determinant = ',det
print '(a,3es12.4)','tune = ',tune
print '(a,3es12.4)','1-tune = ',1-tune


return
end