WSJT-X/lib/slope.f90

42 lines
691 B
Fortran
Raw Normal View History

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