2015-04-22 13:48:03 -04:00
|
|
|
subroutine slope(y,npts,xpk)
|
|
|
|
|
|
|
|
|
|
! Remove best-fit slope from data in y(i). When fitting the straight line,
|
|
|
|
|
! ignore the peak around xpk +/- 2.
|
|
|
|
|
|
|
|
|
|
real y(npts)
|
|
|
|
|
real x(100)
|
|
|
|
|
|
|
|
|
|
do i=1,npts
|
|
|
|
|
x(i)=i
|
|
|
|
|
enddo
|
|
|
|
|
|
|
|
|
|
sumw=0.
|
|
|
|
|
sumx=0.
|
|
|
|
|
sumy=0.
|
|
|
|
|
sumx2=0.
|
|
|
|
|
sumxy=0.
|
|
|
|
|
sumy2=0.
|
|
|
|
|
|
|
|
|
|
do i=1,npts
|
|
|
|
|
if(abs(i-xpk).gt.2.0) then
|
|
|
|
|
sumw=sumw + 1.0
|
|
|
|
|
sumx=sumx + x(i)
|
|
|
|
|
sumy=sumy + y(i)
|
|
|
|
|
sumx2=sumx2 + x(i)**2
|
|
|
|
|
sumxy=sumxy + x(i)*y(i)
|
|
|
|
|
sumy2=sumy2 + y(i)**2
|
|
|
|
|
endif
|
|
|
|
|
enddo
|
|
|
|
|
|
|
|
|
|
delta=sumw*sumx2 - sumx**2
|
|
|
|
|
a=(sumx2*sumy - sumx*sumxy) / delta
|
|
|
|
|
b=(sumw*sumxy - sumx*sumy) / delta
|
|
|
|
|
|
|
|
|
|
do i=1,npts
|
|
|
|
|
y(i)=y(i)-(a + b*x(i))
|
|
|
|
|
enddo
|
|
|
|
|
|
|
|
|
|
return
|
|
|
|
|
end subroutine slope
|
|
|
|
|
|
